Encrypting a digital object on a key ID selected therefor

ABSTRACT

To encrypt a digital object, a key ID is selected for the digital object, and a function f( ) having an input and an output is selected. The selected key ID is then employed as the input to the function f( ), and the output of such function f( ) is employed as the key (KD) for the digital object: f(key ID) key (KD). The digital object is then according to such key (KD), and the encrypted digital object is distributed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.09/290,363, filed Apr. 12, 1999 and entitled “ENFORCEMENT ARCHITECTUREAND METHOD FOR DIGITAL RIGHTS MANAGEMENT”, and U.S. ProvisionalApplication No. 60/126,614, filed Mar. 27, 1999 and entitled“ENFORCEMENT ARCHITECTURE AND METHOD FOR DIGITAL RIGHTS MANAGEMENT”,both of which are hereby incorporated by reference. This applicationclaims the benefit of U.S. Provisional Application No. 60/176,425, filedJan. 14, 2000 under attorney docket number ‘MSFT-0143’ and entitled“ENFORCEMENT ARCHITECTURE AND METHOD FOR DIGITAL RIGHTS MANAGEMENT”,hereby incorporated by reference.

This application is related to and filed concurrently with: U.S. patentapplication Ser. No. ______, Attorney Docket No. MSFT-0117/147,323.1,entitled “PRODUCING A NEW BLACK BOX FOR A DIGITAL RIGHTS MANAGEMENT(DRM) SYSTEM”; U.S. patent application Ser. No. ______, Attorney DocketNo. MSFT-0119/147328.1, entitled “SPECIFYING SECURITY FOR AN ELEMENT BYASSIGNING A SCALED VALUE REPRESENTATIVE OF THE RELATIVE SECURITYTHEREOF”; U.S. patent application Ser. No. ______, Attorney Docket No.MSFT-0135/147325.1, entitled “RELEASING DECRYPTED DIGITAL CONTENT TO ANAUTHENTICATED PATH”; and U.S. patent application Ser. No. ______,Attorney Docket No. MSFT-0136/147326.1, entitled “DIGITAL RIGHTSMANAGEMENT SYSTEM OPERATING ON COMPUTING DEVICE AND HAVING BLACK BOXTIED TO COMPUTING DEVICE”, each of which is hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to an architecture for enforcing rights indigital content. More specifically, the present invention relates tosuch an enforcement architecture that allows access to encrypted digitalcontent only in accordance with parameters specified by license rightsacquired by a user of the digital content.

BACKGROUND OF THE INVENTION

Digital rights management and enforcement is highly desirable inconnection with digital content such as digital audio, digital video,digital text, digital data, digital multimedia, etc., where such digitalcontent is to be distributed to users. Typical modes of distributioninclude tangible devices such as a magnetic (floppy) disk, a magnetictape, an optical (compact) disk (CD), etc., and intangible media such asan electronic bulletin board, an electronic network, the Internet, etc.Upon being received by the user, such user renders or ‘plays’ thedigital content with the aid of an appropriate rendering device such asa media player on a personal computer or the like.

Typically, a content owner or rights-owner, such as an author, apublisher, a broadcaster, etc. (hereinafter “content owner”), wishes todistribute such digital content to a user or recipient in exchange for alicense fee or some other consideration. Such content owner, given thechoice, would likely wish to restrict what the user can do with suchdistributed digital content. For example, the content owner would liketo restrict the user from copying and re-distributing such content to asecond user, at least in a manner that denies the content owner alicense fee from such second user.

In addition, the content owner may wish to provide the user with theflexibility to purchase different types of use licenses at differentlicense fees, while at the same time holding the user to the terms ofwhatever type of license is in fact purchased. For example, the contentowner may wish to allow distributed digital content to be played only alimited number of times, only for a certain total time, only on acertain type of machine, only on a certain type of media player, only bya certain type of user, etc.

However, after distribution has occurred, such content owner has verylittle if any control over the digital content. This is especiallyproblematic in view of the fact that practically every new or recentpersonal computer includes the software and hardware necessary to makean exact digital copy of such digital content, and to download suchexact digital copy to a write-able magnetic or optical disk, or to sendsuch exact digital copy over a network such as the Internet to anydestination.

Of course, as part of the legitimate transaction where the license feewas obtained, the content owner may require the user of the digitalcontent to promise not to re-distribute such digital content. However,such a promise is easily made and easily broken. A content owner mayattempt to prevent such re-distribution through any of several knownsecurity devices, usually involving encryption and decryption. However,there is likely very little that prevents a mildly determined user fromdecrypting encrypted digital content, saving such digital content in anun-encrypted form, and then re-distributing same.

A need exists, then, for providing an enforcement architecture andmethod that allows the controlled rendering or playing of arbitraryforms of digital content, where such control is flexible and definableby the content owner of such digital content. A need also exists forproviding a controlled rendering environment on a computing device suchas a personal computer, where the rendering environment includes atleast a portion of such enforcement architecture. Such controlledrendering environment allows that the digital content will only berendered as specified by the content owner, even though the digitalcontent is to be rendered on a computing device which is not under thecontrol of the content owner.

Further, a need exists for a trusted component running on the computingdevice, where the trusted component enforces the rights of the contentowner on such computing device in connection with a piece of digitalcontent, even against attempts by the user of such computing device toaccess such digital content in ways not permitted by the content owner.As but one example, such a trusted software component prevents a user ofthe computing device from making a copy of such digital content, exceptas otherwise allowed for by the content owner thereof.

SUMMARY OF THE INVENTION

The aforementioned needs are satisfied at least in part by anenforcement architecture and method for digital rights management, wherethe architecture and method enforce rights in protected (secure) digitalcontent available on a medium such as the Internet, an optical disk,etc. For purposes of making content available, the architecture includesa content server from which the digital content is accessible over theInternet or the like in an encrypted form. The content server may alsosupply the encrypted digital content for recording on an optical disk orthe like, wherein the encrypted digital content may be distributed onthe optical disk itself. At the content server, the digital content isencrypted using an encryption key, and public/private key techniques areemployed to bind the digital content with a digital license at theuser's computing device or client machine.

When a user attempts to render the digital content on a computingdevice, the rendering application invokes a Digital Rights Management(DRM) system on such user's computing device. If the user is attemptingto render the digital content for the first time, the DRM system eitherdirects the user to a license server to obtain a license to render suchdigital content in the manner sought, or transparently obtains suchlicense from such license server without any action necessary on thepart of the user. The license includes:

-   -   a decryption key (KD) that decrypts the encrypted digital        content;    -   a description of the rights (play, copy, etc.) conferred by the        license and related conditions (begin date, expiration date,        number of plays, etc.), where such description is in a digitally        readable form; and    -   a digital signature that ensures the integrity of the license.        The user cannot decrypt and render the encrypted digital content        without obtaining such a license from the license server. The        obtained license is stored in a license store in the user's        computing device.

Importantly, the license server only issues a license to a DRM systemthat is ‘trusted’ (i.e., that can authenticate itself). To implement‘trust’, the DRM system is equipped with a ‘black box’ that performsdecryption and encryption functions for such DRM system. The black boxincludes a public/private key pair, a version number and a uniquesignature, all as provided by an approved certifying authority. Thepublic key is made available to the license server for purposes ofencrypting portions of the issued license, thereby binding such licenseto such black box. The private key is available to the black box only,and not to the user or anyone else, for purposes of decryptinginformation encrypted with the corresponding public key. The DRM systemis initially provided with a black box with a public/private key pair,and the user is prompted to download from a black box server an updatedsecure black box when the user first requests a license. The black boxserver provides the updated black box, along with a uniquepublic/private key pair. Such updated black box is written in uniqueexecutable code that will run only on the user's computing device, andis re-updated on a regular basis.

When a user requests a license, the client machine sends the black boxpublic key, version number, and signature to the license server, andsuch license server issues a license only if the version number iscurrent and the signature is valid. A license request also includes anidentification of the digital content for which a license is requestedand a key ID that identifies the decryption key associated with therequested digital content. The license server uses the black box publickey to encrypt the decryption key, and the decryption key to encrypt thelicense terms, then downloads the encrypted decryption key and encryptedlicense terms to the user's computing device along with a licensesignature.

Once the downloaded license has been stored in the DRM system licensestore, the user can render the digital content according to the rightsconferred by the license and specified in the license terms. When arequest is made to render the digital content, the black box is causedto decrypt the decryption key and license terms, and a DRM systemlicense evaluator evaluates such license terms. The black box decryptsthe encrypted digital content only if the license evaluation results ina decision that the requestor is allowed to play such content. Thedecrypted content is provided to the rendering application forrendering.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe embodiments of the present invention, will be better understood whenread in conjunction with the appended drawings. For the purpose ofillustrating the invention, there are shown in the drawings embodimentswhich are presently preferred. As should be understood, however, theinvention is not limited to the precise arrangements andinstrumentalities shown. In the drawings:

FIG. 1 is a block diagram showing an enforcement architecture inaccordance with one embodiment of the present invention;

FIG. 2 is a block diagram of the authoring tool of the architecture ofFIG. 1 in accordance with one embodiment of the present invention;

FIG. 3 is a block diagram of a digital content package having digitalcontent for use in connection with the architecture of FIG. 1 inaccordance with one embodiment of the present invention;

FIG. 4 is a block diagram of the user's computing device of FIG. 1 inaccordance with one embodiment of the present invention;

FIGS. 5A and 5B are flow diagrams showing the steps performed inconnection with the Digital Rights Management (DRM) system of thecomputing device of FIG. 4 to render content in accordance with oneembodiment of the present invention;

FIG. 6 is a flow diagram showing the steps performed in connection withthe DRM system of FIG. 4 to determine whether any valid, enablinglicenses are present in accordance with one embodiment of the presentinvention;

FIG. 7 is a flow diagram showing the steps performed in connection withthe DRM system of FIG. 4 to obtain a license in accordance with oneembodiment of the present invention;

FIG. 8 is a block diagram of a digital license for use in connectionwith the architecture of FIG. 1 in accordance with one embodiment of thepresent invention;

FIG. 9 is a flow diagram showing the steps performed in connection withthe DRM system of FIG. 4 to obtain a new black box in accordance withone embodiment of the present invention;

FIG. 10 is a flow diagram showing the key transaction steps performed inconnection with the DRM system of FIG. 4 to validate a license and apiece of digital content and render the content in accordance with oneembodiment of the present invention;

FIG. 11 is a block diagram showing the license evaluator of FIG. 4 alongwith a Digital Rights License (DRL) of a license and a language enginefor interpreting the DRL in accordance with one embodiment of thepresent invention;

FIG. 12 is a block diagram representing a general purpose computersystem in which aspects of the present invention and/or portions thereofmay be incorporated;

FIG. 13 is a block diagram showing a representative path between arendering application and an ultimate destination;

FIGS. 14-16 are flow diagrams showing various steps performed duringauthentication of the path of FIG. 13;

FIG. 17 is a flow diagrams showing various steps performed duringsecurity approval of the rendering application or a path module of FIG.13;

FIG. 18 is a flow diagram showing various steps performed duringderivation of a decryption key (KD) from a key ID);

FIG. 19 is a block diagram showing apparatus employed to produce a newindividualized bb.dll and a new key file for a black box in oneembodiment of the present invention;

FIGS. 20A-20D are flow diagrams showing various steps performed inconnection with the apparatus shown in FIG. 19;

FIG. 21 is a flow diagram showing various steps performed duringbackup/restore of a black box; and

FIG. 22 is a flow diagram showing various steps performed duringbackup/restore of a digital license.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings in details, wherein like numerals are used toindicate like elements throughout, there is shown in FIG. 1 anenforcement architecture 10 in accordance with one embodiment of thepresent invention. Overall, the enforcement architecture 10 allows anowner of digital content 12 to specify license rules that must besatisfied before such digital content 12 is allowed to be rendered on auser's computing device 14. Such license rules are embodied within adigital license 16 that the user/user's computing device 14(hereinafter, such terms are interchangeable unless circumstancesrequire otherwise) must obtain from the content owner or an agentthereof. The digital content 12 is distributed in an encrypted form, andmay be distributed freely and widely. Preferably, the decrypting key(KD) for decrypting the digital content 12 is included with the license16.

Computer Environment

FIG. 12 and the following discussion are intended to provide a briefgeneral description of a suitable computing environment in which thepresent invention and/or portions thereof may be implemented. Althoughnot required, the invention is described in the general context ofcomputer-executable instructions, such as program modules, beingexecuted by a computer, such as a client workstation or a server.Generally, program modules include routines, programs, objects,components, data structures and the like that perform particular tasksor implement particular abstract data types. Moreover, it should beappreciated that the invention and/or portions thereof may be practicedwith other computer system configurations, including hand-held devices,multi-processor systems, microprocessor-based or programmable consumerelectronics, network PCs, minicomputers, mainframe computers and thelike. The invention may also be practiced in distributed computingenvironments where tasks are performed by remote processing devices thatare linked through a communications network. In a distributed computingenvironment, program modules may be located in both local and remotememory storage devices.

As shown in FIG. 12, an exemplary general purpose computing systemincludes a conventional personal computer 120 or the like, including aprocessing unit 121, a system memory 122, and a system bus 123 thatcouples various system components including the system memory to theprocessing unit 121. The system bus 123 may be any of several types ofbus structures including a memory bus or memory controller, a peripheralbus, and a local bus using any of a variety of bus architectures. Thesystem memory includes read-only memory (ROM) 124 and random accessmemory (RAM) 125. A basic input/output system 126 (BIOS), containing thebasic routines that help to transfer information between elements withinthe personal computer 120, such as during start-up, is stored in ROM124.

The personal computer 120 may further include a hard disk drive 127 forreading from and writing to a hard disk (not shown), a magnetic diskdrive 128 for reading from or writing to a removable magnetic disk 129,and an optical disk drive 130 for reading from or writing to a removableoptical disk 131 such as a CD-ROM or other optical media. The hard diskdrive 127, magnetic disk drive 128, and optical disk drive 130 areconnected to the system bus 123 by a hard disk drive interface 132, amagnetic disk drive interface 133, and an optical drive interface 134,respectively. The drives and their associated computer-readable mediaprovide non-volatile storage of computer readable instructions, datastructures, program modules and other data for the personal computer 20.

Although the exemplary environment described herein employs a hard disk,a removable magnetic disk 129, and a removable optical disk 131, itshould be appreciated that other types of computer readable media whichcan store data that is accessible by a computer may also be used in theexemplary operating environment. Such other types of media include amagnetic cassette, a flash memory card, a digital video disk, aBernoulli cartridge, a random access memory (RAM), a read-only memory(ROM), and the like.

A number of program modules may be stored on the hard disk, magneticdisk 129, optical disk 131, ROM 124 or RAM 125, including an operatingsystem 135, one or more application programs 136, other program modules137 and program data 138. A user may enter commands and information intothe personal computer 120 through input devices such as a keyboard 140and pointing device 142. Other input devices (not shown) may include amicrophone, joystick, game pad, satellite disk, scanner, or the like.These and other input devices are often connected to the processing unit121 through a serial port interface 146 that is coupled to the systembus, but may be connected by other interfaces, such as a parallel port,game port, or universal serial bus (USB). A monitor 147 or other type ofdisplay device is also connected to the system bus 123 via an interface,such as a video adapter 148. In addition to the monitor 147, a personalcomputer typically includes other peripheral output devices (not shown),such as speakers and printers. The exemplary system of FIG. 12 alsoincludes a host adapter 155, a Small Computer System Interface (SCSI)bus 156, and an external storage device 162 connected to the SCSI bus156.

The personal computer 120 may operate in a networked environment usinglogical connections to one or more remote computers, such as a remotecomputer 149. The remote computer 149 may be another personal computer,a server, a router, a network PC, a peer device or other common networknode, and typically includes many or all of the elements described aboverelative to the personal computer 120, although only a memory storagedevice 150 has been illustrated in FIG. 12. The logical connectionsdepicted in FIG. 12 include a local area network (LAN) 151 and a widearea network (WAN) 152. Such networking environments are commonplace inoffices, enterprise-wide computer networks, intranets, and the Internet.

When used in a LAN networking environment, the personal computer 120 isconnected to the LAN 151 through a network interface or adapter 153.When used in a WAN networking environment, the personal computer 120typically includes a modem 154 or other means for establishingcommunications over the wide area network 152, such as the Internet. Themodem 154, which may be internal or external, is connected to the systembus 123 via the serial port interface 146. In a networked environment,program modules depicted relative to the personal computer 120, orportions thereof, may be stored in the remote memory storage device. Itwill be appreciated that the network connections shown are exemplary andother means of establishing a communications link between the computersmay be used.

Architecture

Referring again to FIG. 1, in one embodiment of the present invention,the architecture 10 includes an authoring tool 18, a content-keydatabase 20, a content server 22, a license server 24, and a black boxserver 26, as well as the aforementioned user's computing device 14.

Architecture—Authoring Tool 18

The authoring tool 18 is employed by a content owner to package a pieceof digital content 12 into a form that is amenable for use in connectionwith the architecture 10 of the present invention. In particular, thecontent owner provides the authoring tool 18 with the digital content12, instructions and/or rules that are to accompany the digital content12, and instructions and/or rules as to how the digital content 12 is tobe packaged. The authoring tool 18 then produces a digital contentpackage 12 p having the digital content 12 encrypted according to anencryption/decryption key, and the instructions and/or rules thataccompany the digital content 12.

In one embodiment of the present invention, the authoring tool 18 isinstructed to serially produce several different digital content 12packages 12 p, each having the same digital content 12 encryptedaccording to a different encryption/decryption key. As should beunderstood, having several different packages 12 p with the same digitalcontent 12 may be useful for tracking the distribution of such packages12 p/content 12 (hereinafter simply “digital content 12”, unlesscircumstances require otherwise). Such distribution tracking is notordinarily necessary, but may be used by an investigative authority incases where the digital content 12 has been illegally sold or broadcast.

In one embodiment of the present invention, the encryption/decryptionkey that encrypts the digital content 12 is a symmetric key, in that theencryption key is also the decryption key (KD). As will be discussedbelow in more detail, such decryption key (KD) is delivered to a user'scomputing device 14 in a hidden form as part of a license 16 for suchdigital content 12. Preferably, each piece of digital content 12 isprovided with a content ID (or each package 12 p is provided with apackage ID), each decryption key (KD) has a key ID, and the authoringtool 18 causes the decryption key (KD), key ID, and content ID (orpackage ID) for each piece of digital content 12 (or each package 12 p)to be stored in the content-key database 20. In addition, license dataregarding the types of licenses 16 to be issued for the digital content12 and the terms and conditions for each type of license 16 may bestored in the content-key database 20, or else in another database (notshown). Preferably, the license data can be modified by the contentowner at a later time as circumstances and market conditions mayrequire.

In use, the authoring tool 18 is supplied with information including,among other things:

-   -   the digital content 12 to be packaged;    -   the type and parameters of watermarking and/or fingerprinting to        be employed, if any;    -   the type and parameters of data compression to be employed, if        any;    -   the type and parameters of encryption to be employed;    -   the type and parameters of serialization to be employed, if any;        and    -   the instructions and/or rules that are to accompany the digital        content 12.

As is known, a watermark is a hidden, computer-readable signal that isadded to the digital content 12 as an identifier. A fingerprint is awatermark that is different for each instance. As should be understood,an instance is a version of the digital content 12 that is unique.Multiple copies of any instance may be made, and any copy is of aparticular instance. When a specific instance of digital content 12 isillegally sold or broadcast, an investigative authority can perhapsidentify suspects according to the watermark/fingerprint added to suchdigital content 12.

Data compression may be performed according to any appropriatecompression algorithm without departing from the spirit and scope of thepresent invention. For example, the .mp3 or .wav compression algorithmmay be employed. Of course, the digital content 12 may already be in acompressed state, in which case no additional compression is necessary.

The instructions and/or rules that are to accompany the digital content12 may include practically any appropriate instructions, rules, or otherinformation without departing from the spirit and scope of the presentinvention. As will be discussed below, such accompanyinginstructions/rules/information are primarily employed by the user andthe user's computing device 14 to obtain a license 16 to render thedigital content 12. Accordingly, such accompanyinginstructions/rules/information may include an appropriately formattedlicense acquisition script or the like, as will be described in moredetail below. In addition, or in the alternative, such accompanyinginstructions/rules/information may include ‘preview’ informationdesigned to provide a user with a preview of the digital content 12.

With the supplied information, the authoring tool 18 then produces oneor more packages 12 p corresponding to the digital content 12. Eachpackage 12 p may then be stored on the content server 22 fordistribution to the world.

In one embodiment of the present invention, and referring now to FIG. 2,the authoring tool 18 is a dynamic authoring tool 18 that receives inputparameters which can be specified and operated on. Accordingly, suchauthoring tool 18 can rapidly produce multiple variations of package 12p for multiple pieces of digital content 12. Preferably, the inputparameters are embodied in the form of a dictionary 28, as shown, wherethe dictionary 28 includes such parameters as:

-   -   the name of the input file 29 a having the digital content 12;    -   the type of encoding that is to take place    -   the encryption/decryption key (KD) to be employed,    -   the accompanying instructions/rules/information (‘header        information’) to be packaged with the digital content 12 in the        package 12 p.    -   the type of muxing that is to occur; and    -   the name of the output file 29 b to which the package 12 p based        on the digital content 12 is to be written.

As should be understood, such dictionary 28 is easily and quicklymodifiable by an operator of the authoring tool 18 (human or machine),and therefore the type of authoring performed by the authoring tool 18is likewise easily and quickly modifiable in a dynamic manner. In oneembodiment of the present invention, the authoring tool 18 includes anoperator interface (not shown) displayable on a computer screen to ahuman operator. Accordingly, such operator may modify the dictionary 28by way of the interface, and further may be appropriately aided and/orrestricted in modifying the dictionary 28 by way of the interface.

In the authoring tool 18, and as seen in FIG. 2, a source filter 18 areceives the name of the input file 29 a having the digital content 12from the dictionary 28, and retrieves such digital content 12 from suchinput file and places the digital content 12 into a memory 29 c such asa RAM or the like. An encoding filter 18 b then performs encoding on thedigital content 12 in the memory 29 c to transfer the file from theinput format to the output format according to the type of encodingspecified in the dictionary 28 (i.e., .wav to .asp, .mp3 to asp, etc.),and places the encoded digital content 12 in the memory 29 c. As shown,the digital content 12 to be packaged (music, e.g.) is received in acompressed format such as the .wav or .mp3 format, and is transformedinto a format such as the asp (active streaming protocol) format. Ofcourse, other input and output formats may be employed without departingfrom the spirit and scope of the present invention.

Thereafter, an encryption filter 118 c encrypts the encoded digitalcontent 12 in the memory 29 c according to the encryption/decryption key(KD) specified in the dictionary 28, and places the encrypted digitalcontent 12 in the memory 29 c. A header filter 18 d then adds the headerinformation specified in the dictionary 28 to the encrypted digitalcontent 12 in the memory 29 c.

As should be understood, depending on the situation, the package 12 pmay include multiple streams of temporally aligned digital content 12(one stream being shown in FIG. 2), where such multiple streams aremultiplexed (i.e., ‘muxed’). Accordingly, a mux filter 18 e performsmuxing on the header information and encrypted digital content 12 in thememory 29 c according to the type of muxing specified in the dictionary28, and places the result in the memory 29 c. A file writer filter 18 fthen retrieves the result from the memory 29 c and writes such result tothe output file 29 b specified in the dictionary 28 as the package 12 p.

It should be noted that in certain circumstances, the type of encodingto be performed will not normally change. Since the type of muxingtypically is based on the type of encoding, it is likewise the case thatthe type of muxing will not normally change, either. If this is in factthe case, the dictionary 28 need not include parameters on the type ofencoding and/or the type of muxing. Instead, it is only necessary thatthe type of encoding be ‘hardwired’ into the encoding filter and/or thatthe type of muxing be ‘hardwired’ into the mux filter. Of course, ascircumstance require, the authoring tool 18 may not include all of theaforementioned filters, or may include other filters, and any includedfilter may be hardwired or may perform its function according toparameters specified in the dictionary 28, all without departing fromthe spirit and scope of the present invention.

Preferably, the authoring tool 18 is implemented on an appropriatecomputer, processor, or other computing machine by way of appropriatesoftware. The structure and operation of such machine and such softwareshould be apparent based on the disclosure herein and therefore do notrequire any detailed discussion in the present disclosure.

Architecture—Content Server 22

Referring again to FIG. 1, in one embodiment of the present invention,the content server 22 distributes or otherwise makes available forretrieval the packages 12 p produced by the authoring tool 18. Suchpackages 12 p may be distributed as requested by the content server 22by way of any appropriate distribution channel without departing fromthe spirit and scope of the present invention. For example, suchdistribution channel may be the Internet or another network, anelectronic bulletin board, electronic mail, or the like. In addition,the content server 22 may be employed to copy the packages 12 p ontomagnetic or optical disks or other storage devices, and such storagedevices may then be distributed.

It will be appreciated that the content server 22 distributes packages12 p without regard to any trust or security issues. As discussed below,such issues are dealt with in connection with the license server 24 andthe relationship between such license server 24 and the user's computingdevice 14. In one embodiment of the present invention, the contentserver 22 freely releases and distributes packages 12 p having digitalcontent 12 to any distributee requesting same. However, the contentserver 22 may also release and distribute such packages 12 p in arestricted manner without departing from the spirit and scope of thepresent invention. For example, the content server 22 may first requirepayment of a pre-determined distribution fee prior to distribution, ormay require that a distributee identify itself, or may indeed make adetermination of whether distribution is to occur based on anidentification of the distributee.

In addition, the content server 22 may be employed to perform inventorymanagement by controlling the authoring tool 18 to generate a number ofdifferent packages 12 p in advance to meet an anticipated demand. Forexample, the server could generate 100 packages 12 p based on the samedigital content 12, and serve each package 12 p 10 times. As supplies ofpackages 12 p dwindle to 20, for example, the content server 22 may thendirect the authoring tool 18 to generate 80 additional packages 12 p,again for example.

Preferably, the content server 22 in the architecture 10 has a uniquepublic/private key pair (PU-CS, PR-CS) that is employed as part of theprocess of evaluating a license 16 and obtaining a decryption key (KD)for decrypting corresponding digital content 12, as will be explained inmore detail below. As is known, a public/private key pair is anasymmetric key, in that what is encrypted in one of the keys in the keypair can only be decrypted by the other of the keys in the key pair. Ina public/private key pair encryption system, the public key may be madeknown to the world, but the private key should always be held inconfidence by the owner of such private key. Accordingly, if the contentserver 22 encrypts data with its private key (PR-CS), it can send theencrypted data out into the world with its public key (PU-CS) fordecryption purposes. Correspondingly, if an external device wants tosend data to the content server 22 so that only such content server 22can decrypt such data, such external device must first obtain the publickey of the content server 22 (PU-CS) and then must encrypt the data withsuch public key. Accordingly, the content server 22 (and only thecontent server 22) can then employ its private key (PR-CS) to decryptsuch encrypted data.

As with the authoring tool 18, the content server 22 is implemented onan appropriate computer, processor, or other computing machine by way ofappropriate software. The structure and operation of such machine andsuch software should be apparent based on the disclosure herein andtherefore do not require any detailed discussion in the presentdisclosure. Moreover, in one embodiment of the present invention, theauthoring tool 18 and the content server 22 may reside on a singlecomputer, processor, or other computing machine, each in a separate workspace. It should be recognized, moreover, that the content server 22 mayin certain circumstances include the authoring tool 18 and/or performthe functions of the authoring tool 18, as discussed above.

Structure of Digital Content Package 12 p

Referring now to FIG. 3, in one embodiment of the present invention, thedigital content package 12 p as distributed by the content server 22includes:

-   -   the digital content 12 encrypted with the encryption/decryption        key (KD), as was discussed above (i.e., (KD(CONTENT)));    -   the content ID (or package ID) of such digital content 12 (or        package 12 p);    -   the key ID of the decryption key (KD);    -   license acquisition information, preferably in an un-encrypted        form; and    -   the key KD encrypting the content server 22 public key (PU-CS),        signed by the content server 22 private key (PR-CS) (i.e., (KD        (PU-CS) S (PR-CS))).

With regard to (KD (PU-CS) S (PR-CS)), it is to be understood that suchitem is to be used in connection with validating the digital content 12and/or package 12 p, as will be explained below. Unlike a certificatewith a digital signature (see below), the key (PU-CS) is not necessaryto get at (KD (PU-CS)). Instead, the key (PU-CS) is obtained merely byapplying the decryption key (KD). Once so obtained, such key (PU-CS) maybe employed to test the validity of the signature (S (PR-CS)).

It should also be understood that for such package 12 p to beconstructed by the authoring tool 18, such authoring tool 18 mustalready possess the license acquisition information and (KD (PU-CS) S(PR-CS)), presumably as header information supplied by the dictionary28. Moreover, the authoring tool 18 and the content server 22 mustpresumably interact to construct (KD (PU-CS) S (PR-CS)). Suchinteraction may for example include the steps of:

-   -   the content server 22 sending (PU-CS) to the authoring tool 18;    -   the authoring tool 18 encrypting (PU-CS) with (KD) to produce        (KD (PU-CS));    -   the authoring tool 18 sending (KD (PU-CS)) to the content server        22;    -   the content server 22 signing (KD (PU-CS)) with (PR-CS) to        produce (KD (PU-CS) S (PR-CS)); and    -   the content server 22 sending (KD (PU-CS) S (PR-CS)) to the        authoring tool 18.        Architecture—License Server 24

Referring again to FIG. 1, in one embodiment of the present invention,the license server 24 performs the functions of receiving a request fora license 16 from a user's computing device 14 in connection with apiece of digital content 12, determining whether the user's computingdevice 14 can be trusted to honor an issued license 16, negotiating sucha license 16, constructing such license 16, and transmitting suchlicense 16 to the user's computing device 14. Preferably, suchtransmitted license 16 includes the decryption key (KD) for decryptingthe digital content 12. Such license server 24 and such functions willbe explained in more detail below. Preferably, and like the contentserver 22, the license server 24 in the architecture 10 has a uniquepublic/private key pair (PU-LS, PR-LS) that is employed as part of theprocess of evaluating a license 16 and obtaining a decryption key (KD)for decrypting corresponding digital content 12, as will be explained inmore detail below.

As with the authoring tool 18 and the content server 22, the licenseserver 24 is implemented on an appropriate computer, processor, or othercomputing machine by way of appropriate software. The structure andoperation of such machine and such software should be apparent based onthe disclosure herein and therefore do not require any detaileddiscussion in the present disclosure. Moreover, in one embodiment of thepresent invention the authoring tool 18 and/or the content server 22 mayreside on a single computer, processor, or other computing machinetogether with the license server 24, each in a separate work space.

In one embodiment of the present invention, prior to issuance of alicense 16, the license server 24 and the content server 22 enter intoan agency agreement or the like, wherein the license server 24 in effectagrees to be the licensing authority for at least a portion of thedigital content 12 distributed by the content server 22. As should beunderstood, one content server 22 may enter into an agency agreement orthe like with several license servers 24, and/or one license server 24may enter into an agency agreement or the like with several contentservers 22, all without departing from the spirit and scope of thepresent invention.

Preferably, the license server 24 can show to the world that it does infact have the authority to issue a license 16 for digital content 12distributed by the content server 22. To do so, it is preferable thatthe license server 24 send to the content server 22 the license server24 public key (PU-LS), and that the content server 22 then send to thelicense server 24 a digital certificate containing PU-LS as the contentssigned by the content server 22 private key (CERT (PU-LS) S (PR-CS)). Asshould be understood, the contents (PU-LS) in such certificate can onlybe accessed with the content server 22 public key (PU-CS). As shouldalso be understood, in general, a digital signature of underlying datais an encrypted form of such data, and will not match such data whendecrypted if such data has been adulterated or otherwise modified.

As a licensing authority in connection with a piece of digital content12, and as part of the licensing function, the license server 24 musthave access to the decryption key (KD) for such digital content 12.Accordingly, it is preferable that license server 24 have access to thecontent-key database 20 that has the decryption key (KD), key ID, andcontent ID (or package ID) for such digital content 12 (or package 12p).

Architecture—Black Box Server 26

Still referring to FIG. 1, in one embodiment of the present invention,the black box server 26 performs the functions of installing and/orupgrading a new black box 30 in a user's computing device 14. As will beexplained in more detail below, the black box 30 performs encryption anddecryption functions for the user's computing device 14. As will also beexplained in more detail below, the black box 30 is intended to besecure and protected from attack. Such security and protection isprovided, at least in part, by upgrading the black box 30 to a newversion as necessary by way of the black box server 26, as will beexplained in more detail below.

As with the authoring tool 18, the content server 22, and the licenseserver 24, the black box server 26 is implemented on an appropriatecomputer, processor, or other computing machine by way of appropriatesoftware. The structure and operation of such machine and such softwareshould be apparent based on the disclosure herein and therefore do notrequire any detailed discussion in the present disclosure. Moreover, inone embodiment of the present invention the license server 24, theauthoring tool 18, and/or the content server 22 may reside on a singlecomputer, processor, or other computing machine together with the blackbox server 26, each in a separate work space. Note, though, that forsecurity purposes, it may be wise to have the black box server 26 on aseparate machine.

Architecture—User's Computing Device 14

Referring now to FIG. 4, in one embodiment of the present invention, theuser's computing device 14 is a personal computer or the like, havingelements including a keyboard, a mouse, a screen, a processor, RAM, ROM,a hard drive, a floppy drive, a CD player, and/or the like. However, theuser's computing device 14 may also be a dedicated viewing device suchas a television or monitor, a dedicated audio device such as a stereo orother music player, a dedicated printer, or the like, among otherthings, all without departing from the spirit and scope of the presentinvention.

The content owner for a piece of digital content 12 must trust that theuser's computing device 14 will abide by the rules specified by suchcontent owner, i.e. that the digital content 12 will not be renderedunless the user obtains a license 16 that permits the rendering in themanner sought. Preferably, then, the user's computing device 14 mustprovide a trusted component or mechanism 32 that can satisfy to thecontent owner that such computing device 14 will not render the digitalcontent 12 except according to the license rules embodied in the license16 associated with the digital content 12 and obtained by the user.

Here, the trusted mechanism 32 is a Digital Rights Management (DRM)system 32 that is enabled when a user requests that a piece of digitalcontent 12 be rendered, that determines whether the user has a license16 to render the digital content 12 in the manner sought, thateffectuates obtaining such a license 16 if necessary, that determineswhether the user has the right to play the digital content 12 accordingto the license 16, and that decrypts the digital content 12 forrendering purposes if in fact the user has such right according to suchlicense 16. The contents and function of the DRM system 32 on the user'scomputing device 14 and in connection with the architecture 10 aredescribed below.

DRM System 32

The DRM system 32 performs four main functions with the architecture 10disclosed herein: (1) content acquisition, (2) license acquisition, (3)content rendering, and (4) black box 30 installation/update. Preferably,any of the functions can be performed at any time, although it isrecognized that some of the functions already require that digitalcontent 12 be acquired.

DRM System 32—Content Acquisition

Acquisition of digital content 12 by a user and/or the user's computingdevice 14 is typically a relatively straight-forward matter andgenerally involves placing a file having encrypted digital content 12 onthe user's computing device 14. Of course, to work with the architecture10 and the DRM system 32 disclosed herein, it is necessary that theencrypted digital content 12 be in a form that is amenable to sucharchitecture 10 and DRM system 32, such as the digital package 12 p aswill be described below.

As should be understood, the digital content 12 may be obtained in anymanner from a content server 22, either directly or indirectly, withoutdeparting from the spirit and scope of the present invention. Forexample, such digital content 12 may be downloaded from a network suchas the Internet, located on an obtained optical or magnetic disk or thelike, received as part of an E-mail message or the like, or downloadedfrom an electronic bulletin board or the like.

Such digital content 12, once obtained, is preferably stored in a mannersuch that the obtained digital content 12 is accessible by a renderingapplication 34 (to be described below) running on the computing device14, and by the DRM system 32. For example, the digital content 12 may beplaced as a file on a hard drive (not shown) of the user's computingdevice 14, or on a network server (not shown) accessible to thecomputing device 14. In the case where the digital content 12 isobtained on an optical or magnetic disk or the like, it may only benecessary that such disk be present in an appropriate drive (not shown)coupled to the user's computing device 14.

In the present invention, it is not envisioned that any special toolsare necessary to acquire digital content 12, either from the contentserver 22 as a direct distribution source or from some intermediary asan indirect distribution source. That is, it is preferable that digitalcontent 12 be as easily acquired as any other data file. However, theDRM system 32 and/or the rendering application 34 may include aninterface (not shown) designed to assist the user in obtaining digitalcontent 12. For example, the interface may include a web browserespecially designed to search for digital content 12, links topre-defined Internet web sites that are known to be sources of digitalcontent 12, and the like.

DRM System 32—Content Rendering, Part 1

Referring now to FIG. 5A, in one embodiment of the present invention,assuming the encrypted digital content 12 has been distributed to andreceived by a user and placed by the user on the computing device 14 inthe form of a stored file, the user will attempt to render the digitalcontent 12 by executing some variation on a render command (step 501).For example, such render command may be embodied as a request to ‘play’or ‘open’ the digital content 12. In some computing environments, suchas for example the “MICROSOFT WINDOWS” operating system, distributed byMICROSOFT Corporation of Redmond, Wash., such play or open command maybe as simple as ‘clicking’ on an icon representative of the digitalcontent 12. Of course, other embodiments of such render command may beemployed without departing from the spirit and scope of the presentinvention. In general, such render command may be considered to beexecuted whenever a user directs that a file having digital content 12be opened, run, executed, and/or the like.

Importantly, and in addition, such render command may be embodied as arequest to copy the digital content 12 to another form, such as to aprinted form, a visual form, an audio form, etc. As should beunderstood, the same digital content 12 may be rendered in one form,such as on a computer screen, and then in another form, such as aprinted document. In the present invention, each type of rendering isperformed only if the user has the right to do so, as will be explainedbelow.

In one embodiment of the present invention, the digital content 12 is inthe form of a digital file having a file name ending with an extension,and the computing device 14 can determine based on such extension tostart a particular kind of rendering application 34. For example, if thefile name extension indicates that the digital content 12 is a textfile, the rendering application 34 is some form of word processor suchas the “MICROSOFT WORD”, distributed by MICROSOFT Corporation ofRedmond, Wash. Likewise, if the file name extension indicates that thedigital content 12 is an audio, video, and/or multimedia file, therendering application 34 is some form of multimedia player, such as“MICROSOFT MEDIA PLAYER”, also distributed by MICROSOFT Corporation ofRedmond, Wash.

Of course, other methods of determining a rendering application may beemployed without departing from the spirit and scope of the presentinvention. As but one example, the digital content 12 may containmeta-data in an un-encrypted form (i.e., the aforementioned headerinformation), where the meta-data includes information on the type ofrendering application 34 necessary to render such digital content 12.

Preferably, such rendering application 34 examines the digital content12 associated with the file name and determines whether such digitalcontent 12 is encrypted in a rights-protected form (steps 503, 505). Ifnot protected, the digital content 12 may be rendered without furtherado (step 507). If protected, the rendering application 34 determinesfrom the encrypted digital content 12 that the DRM system 32 isnecessary to play such digital content 12. Accordingly, such renderingapplication 34 directs the user's computing device 14 to run the DRMsystem 32 thereon (step 509). Such rendering application 34 then callssuch DRM system 32 to decrypt the digital content 12 (step 511). As willbe discussed in more detail below, the DRM system 32 in fact decryptsthe digital content 12 only if the user has a valid license 16 for suchdigital content 12 and the right to play the digital content 12according to the license rules in the valid license 16. Preferably, oncethe DRM system 32 has been called by the rendering application 34, suchDRM system 32 assumes control from the rendering application 34, atleast for purposes of determining whether the user has a right to playsuch digital content 12 (step 513).

DRM System 32 Components

In one embodiment of the present invention, and referring again to FIG.4, the DRM system 32 includes a license evaluator 36, the black box 30,a license store 38, and a state store 40.

DRM System 32 Components—License Evaluator 36

The license evaluator 36 locates one or more licenses 16 that correspondto the requested digital content 12, determines whether such licenses 16are valid, reviews the license rules in such valid licenses 16, anddetermines based on the reviewed license rules whether the requestinguser has the right to render the requested digital content 12 in themanner sought, among other things. As should be understood, the licenseevaluator 36 is a trusted component in the DRM system 32. In the presentdisclosure, to be ‘trusted’ means that the license server 24 (or anyother trusting element) is satisfied that the trusted element will carryout the wishes of the owner of the digital content 12 according to therights description in the license 16, and that a user cannot easilyalter such trusted element for any purpose, nefarious or otherwise.

The license evaluator 36 has to be trusted in order to ensure that suchlicense evaluator 36 will in fact evaluate a license 16 properly, and toensure that such license evaluator 36 has not been adulterated orotherwise modified by a user for the purpose of bypassing actualevaluation of a license 16. Accordingly, the license evaluator 36 is runin a protected or shrouded environment such that the user is deniedaccess to such license evaluator 36. Other protective measures may ofcourse be employed in connection with the license evaluator 36 withoutdeparting from the spirit and scope of the present invention.

DRM System 32 Components—Black Box 30

Primarily, and as was discussed above, the black box 30 performsencryption and decryption functions in the DRM system 32. In particular,the black box 30 works in conjunction with the license evaluator 36 todecrypt and encrypt certain information as part of the licenseevaluation function. In addition, once the license evaluator 36determines that a user does in fact have the right to render therequested digital content 12 in the manner sought, the black box 30 isprovided with a decryption key (KD) for such digital content 12, andperforms the function of decrypting such digital content 12 based onsuch decryption key (KD).

The black box 30 is also a trusted component in the DRM system 32. Inparticular, the license server 24 must trust that the black box 30 willperform the decryption function only in accordance with the licenserules in the license 16, and also trust that such black box 30 will notoperate should it become adulterated or otherwise modified by a user forthe nefarious purpose of bypassing actual evaluation of a license 16.Accordingly, the black box 30 is also run in a protected or shroudedenvironment such that the user is denied access to such black box 30.Again, other protective measures may be employed in connection with theblack box 30 without departing from the spirit and scope of the presentinvention. Preferably, and like the content server 22 and license server24, the black box 30 in the DRM system 32 has a unique public/privatekey pair (PU-BB, PR-BB) that is employed as part of the process ofevaluating the license 16 and obtaining a decryption key (KD) fordecrypting the digital content 12, as will be described in more detailbelow.

DRM System 32 Components—License Store 38

The license store 38 stores licenses 16 received by the DRM system 32for corresponding digital content 12. The license store 38 itself neednot be trusted since the license store 38 merely stores licenses 16,each of which already has trust components built thereinto, as will bedescribed below. In one embodiment of the present invention, the licensestore 38 is merely a sub-directory of a drive such as a hard disk driveor a network drive. However, the license store 38 may be embodied in anyother form without departing from the spirit and scope of the presentinvention, so long as such license store 38 performs the function ofstoring licenses 16 in a location relatively convenient to the DRMsystem 32.

DRM System 32 Components—State Store 40

The state store 40 performs the function of maintaining stateinformation corresponding to licenses 16 presently or formerly in thelicense store 38. Such state information is created by the DRM system 32and stored in the state store 40 as necessary. For example, if aparticular license 16 only allows a pre-determined number of renderingsof a piece of corresponding digital content 12, the state store 40maintains state information on how many renderings have in fact takenplace in connection with such license 16. The state store 40 continuesto maintain state information on licenses 16 that are no longer in thelicense store 38 to avoid the situation where it would otherwise beadvantageous to delete a license 16 from the license store 38 and thenobtain an identical license 16 in an attempt to delete the correspondingstate information from the state store 40.

The state store 40 also has to be trusted in order to ensure that theinformation stored therein is not reset to a state more favorable to auser. Accordingly, the state store 40 is likewise run in a protected orshrouded environment such that the user is denied access to such statestore 40. Once again, other protective measures may of course beemployed in connection with the state store 40 without departing fromthe spirit and scope of the present invention. For example, the statestore 40 may be stored by the DRM system 32 on the computing device 14in an encrypted form.

DRM System 32—Content Rendering, Part 2

Referring again to FIG. 5A, and again discussing content rendering inone embodiment of the present invention, once the DRM system 32 hasassumed control from the calling rendering application 34, such DRMsystem 32 then begins the process of determining whether the user has aright to render the requested digital content 12 in the manner sought.In particular, the DRM system 32 either locates a valid, enablinglicense 16 in the license store (steps 515, 517) or attempts to acquirea valid, enabling license 16 from the license server 24 (i.e. performsthe license acquisition function as discussed below and as shown in FIG.7).

As a first step, and referring now to FIG. 6, the license evaluator 36of such DRM system 32 checks the license store 38 for the presence ofone or more received licenses 16 that correspond to the digital content12 (step 601). Typically, the license 16 is in the form of a digitalfile, as will be discussed below, although it will be recognized thatthe license 16 may also be in other forms without departing from thespirit and scope of the present invention. Typically, the user willreceive the digital content 12 without such license 16, although it willlikewise be recognized that the digital content 12 may be received witha corresponding license 16 without departing from the spirit and scopeof the present invention.

As was discussed above in connection with FIG. 3, each piece of digitalcontent 12 is in a package 12 p with a content ID (or package ID)identifying such digital content 12 (or package 12 p), and a key IDidentifying the decryption key (KD) that will decrypt the encrypteddigital content 12. Preferably, the content ID (or package ID) and thekey ID are in an un-encrypted form. Accordingly, and in particular,based on the content ID of the digital content 12, the license evaluator36 looks for any license 16 in the license store 38 that contains anidentification of applicability to such content ID. Note that multiplesuch licenses 16 may be found, especially if the owner of the digitalcontent 12 has specified several different kinds of licenses 16 for suchdigital content 12, and the user has obtained multiple ones of suchlicenses 16. If in fact the license evaluator 36 does not find in thelicense store 38 any license 16 corresponding to the requested digitalcontent 12, the DRM system 32 may then perform the function of licenseacquisition (step 519 of FIG. 5), to be described below.

Assume now that the DRM system 32 has been requested to render a pieceof digital content 12, and one or more licenses 16 corresponding theretoare present in the license store 38. In one embodiment of the presentinvention, then, the license evaluator 36 of the DRM system 32 proceedsto determine for each such license 16 whether such license 16 itself isvalid (steps 603 and 605 of FIG. 6). Preferably, and in particular, eachlicense 16 includes a digital signature 26 based on the content 28 ofthe license 16. As should be understood, the digital signature 26 willnot match the license 16 if the content 28 has been adulterated orotherwise modified. Thus, the license evaluator 36 can determine basedon the digital signature 26 whether the content 28 is in the form thatit was received from the license server 24 (i.e., is valid). If no validlicense 16 is found in the license store 38, the DRM system 32 may thenperform the license acquisition function described below to obtain sucha valid license 16.

Assuming that one or more valid licenses 16 are found, for each validlicense 16, the license evaluator 36 of the DRM system 32 nextdetermines whether such valid license 16 gives the user the right torender the corresponding digital content 12 in the manner desired (i.e.,is enabling) (steps 607 and 609). In particular, the license evaluator36 determines whether the requesting user has the right to play therequested digital content 12 based on the rights description in eachlicense 16 and based on what the user is attempting to do with thedigital content 12. For example, such rights description may allow theuser to render the digital content 12 into a sound, but not into adecrypted digital copy.

As should be understood, the rights description in each license 16specifies whether the user has rights to play the digital content 12based on any of several factors, including who the user is, where theuser is located, what type of computing device 14 the user is using,what rendering application 34 is calling the DRM system 32, the date,the time, etc. In addition, the rights description may limit the license16 to a pre-determined number of plays, or pre-determined play time, forexample. In such case, the DRM system 32 must refer to any stateinformation with regard to the license 16, (i.e., how many times thedigital content 12 has been rendered, the total amount of time thedigital content 12 has been rendered, etc.), where such stateinformation is stored in the state store 40 of the DRM system 32 on theuser's computing device 14.

Accordingly, the license evaluator 36 of the DRM system 32 reviews therights description of each valid license 16 to determine whether suchvalid license 16 confers the rights sought to the user. In doing so, thelicense evaluator 36 may have to refer to other data local to the user'scomputing device 14 to perform a determination of whether the user hasthe rights sought. As seen in FIG. 4, such data may include anidentification 42 of the user's computing device (machine) 14 andparticular aspects thereof, an identification 44 of the user andparticular aspects thereof, an identification of the renderingapplication 34 and particular aspects thereof, a system clock 46, andthe like. If no valid license 16 is found that provides the user withthe right to render the digital content 12 in the manner sought, the DRMsystem 32 may then perform the license acquisition function describedbelow to obtain such a license 16, if in fact such a license 16 isobtainable.

Of course, in some instances the user cannot obtain the right to renderthe digital content 12 in the manner requested, because the contentowner of such digital content 12 has in effect directed that such rightnot be granted. For example, the content owner of such digital content12 may have directed that no license 16 be granted to allow a user toprint a text document, or to copy a multimedia presentation into anun-encrypted form. In one embodiment of the present invention, thedigital content 12 includes data on what rights are available uponpurchase of a license 16, and types of licenses 16 available. However,it will be recognized that the content owner of a piece of digitalcontent 12 may at any time change the rights currently available forsuch digital content 12 by changing the licenses 16 available for suchdigital content 12.

DRM System 32—License Acquisition

Referring now to FIG. 7, if in fact the license evaluator 36 does notfind in the license store 38 any valid, enabling license 16corresponding to the requested digital content 12, the DRM system 32 maythen perform the function of license acquisition. As shown in FIG. 3,each piece of digital content 12 is packaged with information in anun-encrypted form regarding how to obtain a license 16 for renderingsuch digital content 12 (i.e., license acquisition information).

In one embodiment of the present invention, such license acquisitioninformation may include (among other things) types of licenses 16available, and one or more Internet web sites or other site informationat which one or more appropriate license servers 24 may be accessed,where each such license server 24 is in fact capable of issuing alicense 16 corresponding to the digital content 12. Of course, thelicense 16 may be obtained in other manners without departing from thespirit and scope of the present invention. For example, the license 16may be obtained from a license server 24 at an electronic bulletinboard, or even in person or via regular mail in the form of a file on amagnetic or optical disk or the like.

Assuming that the location for obtaining a license 16 is in fact alicense server 24 on a network, the license evaluator 36 thenestablishes a network connection to such license server 24 based on theweb site or other site information, and then sends a request for alicense 16 from such connected license server 24 (steps 701, 703). Inparticular, once the DRM system 32 has contacted the license server 24,such DRM system 32 transmits appropriate license request information 36to such license server 24. In one embodiment of the present invention,such license 16 request information 36 may include:

-   -   the public key of the black box 30 of the DRM system 32 (PU-BB);    -   the version number of the black box 30 of the DRM system 32;    -   a certificate with a digital signature from a certifying        authority certifying the black box 30 (where the certificate may        in fact include the aforementioned public key and version number        of the black box 30);    -   the content ID (or package ID) that identifies the digital        content 12 (or package 12 p);    -   the key ID that identifies the decryption key (KD) for        decrypting the digital content 12;    -   the type of license 16 requested (if in fact multiple types are        available);    -   the type of rendering application 34 that requested rendering of        the digital content 12;        and/or the like, among other things. Of course, greater or        lessor amounts of license 16 request information 36 may be        transmitted to the license server 24 by the DRM system 32        without departing from the spirit and scope of the present        invention. For example, information on the type of rendering        application 34 may not be necessary, while additional        information about the user and/or the user's computing device 14        may be necessary.

Once the license server 24 has received the license 16 requestinformation 36 from the DRM system 32, the license server 24 may thenperform several checks for trust/authentication and for other purposes.In one embodiment of the present invention, such license server 24checks the certificate with the digital signature of the certifyingauthority to determine whether such has been adulterated or otherwisemodified (steps 705, 707). If so, the license server 24 refuses to grantany license 16 based on the request information 36. The license server24 may also maintain a list of known ‘bad’ users and/or user's computingdevices 14, and may refuse to grant any license 16 based on a requestfrom any such bad user and/or bad user's computing device 14 on thelist. Such ‘bad’ list may be compiled in any appropriate manner withoutdeparting from the spirit and scope of the present invention.

Based on the received request and the information associated therewith,and particularly based on the content ID (or package ID) in the licenserequest information, the license server 24 can interrogate thecontent-key database 20 (FIG. 1) and locate a record corresponding tothe digital content 12 (or package 12 p) that is the basis of therequest. As was discussed above, such record contains the decrytion key(KD), key ID, and content ID for such digital content 12. In addition,such record may contain license data regarding the types of licenses 16to be issued for the digital content 12 and the terms and conditions foreach type of license 16. Alternatively, such record may include apointer, link, or reference to a location having such additionalinformation.

As mentioned above, multiple types of licenses 16 may be available. Forexample, for a relatively small license fee, a license 16 allowing alimited number of renderings may be available. For a relatively greaterlicense fee, a license 16 allowing unlimited renderings until anexpiration date may be available. For a still greater license fee, alicense 16 allowing unlimited renderings without any expiration date maybe available. Practically any type of license 16 having any kind oflicense terms may be devised and issued by the license server 24 withoutdeparting from the spirit and scope of the present invention.

In one embodiment of the present invention, the request for a license 16is accomplished with the aid of a web page or the like as transmittedfrom the license server 24 to the user's computing device 14.Preferably, such web page includes information on all types of licenses16 available from the license server 24 for the digital content 12 thatis the basis of the license 16 request.

In one embodiment of the present invention, prior to issuing a license16, the license server 24 checks the version number of the black box 30to determine whether such black box 30 is relatively current (steps 709,711). As should be understood, the black box 30 is intended to be secureand protected from attacks from a user with nefarious purposes (i.e., toimproperly render digital content 12 without a license 16, or outsidethe terms of a corresponding license 16). However, it is to berecognized that no system and no software device is in fact totallysecure from such an attack.

As should also be understood, if the black box 30 is relatively current,i.e., has been obtained or updated relatively recently, it is lesslikely that such black box 30 has been successfully attacked by such anefarious user. Preferably, and as a matter of trust, if the licenseserver 24 receives a license request with request information 36including a black box 30 version number that is not relatively current,such license server 24 refuses to issue the requested license 16 untilthe corresponding black box 30 is upgraded to a current version, as willbe described below. Put simply, the license server 24 will not trustsuch black box 30 unless such black box 30 is relatively current.

In the context of the black box 30 of the present invention, the term‘current’ or ‘relatively current’ may have any appropriate meaningwithout departing from the spirit and scope of the present invention,consistent with the function of providing trust in the black box 30based on the age or use thereof. For example, ‘current’ may be definedaccording to age (i.e., less than one month old). As an alternativeexample, ‘current’ may be defined based on a number of times that theblack box 30 has decrypted digital content 12 (i.e., less than 200instances of decryption). Moreover, ‘current’ may be based on policy asset by each license server 24, where one license server 24 may define‘current’ differently from another license server 24, and a licenseserver 24 may further define ‘current’ differently depending on thedigital content 12 for which a license 16 is requested, or depending onthe type of license 16 requested, among other things.

Assuming that the license server 24 is satisfied from the version numberof a black box 30 or other indicia thereof that such black box 30 iscurrent, the license server 24 then proceeds to negotiate terms andconditions for the license 16 with the user (step 713). Alternatively,the license server 24 negotiates the license 16 with the user, thensatisfies itself from the version number of the black box 30 that suchblack box 30 is current (i.e., performs step 713, then step 711). Ofcourse, the amount of negotiation varies depending on the type oflicense 16 to be issued, and other factors. For example, if the licenseserver 24 is merely issuing a paid-up unlimited use license 16, verylittle need be negotiated. On the other hand, if the license 16 is to bebased on such items as varying values, sliding scales, break points, andother details, such items and details may need to be worked out betweenthe license server 24 and the user before the license 16 can be issued.

As should be understood, depending on the circumstances, the licensenegotiation may require that the user provide further information to thelicense server 24 (for example, information on the user, the user'scomputing device 14, etc.). Importantly, the license negotiation mayalso require that the user and the license server 24 determine amutually acceptable payment instrument (a credit account, a debitaccount, a mailed check, etc.) and/or payment method (paid-upimmediately, spread over a period of time, etc.), among other things.

Once all the terms of the license 16 have been negotiated and agreed toby both the license server 24 and user (step 715), a digital license 16is generated by the license server 24 (step 719), where such generatedlicense 16 is based at least in part on the license request, the blackbox 30 public key (PU-BB), and the decryption key (KD) for the digitalcontent 12 that is the basis of the request as obtained from thecontent-key database 20. In one embodiment of the present invention, andas seen in FIG. 8, the generated license 16 includes:

-   -   the content ID of the digital content 12 to which the license 16        applies;    -   a Digital Rights License (DRL) 48 (i.e., the rights description        or actual terms and conditions of the license 16 written in a        predetermined form that the license evaluator 36 can        interrogate), perhaps encrypted with the decryption key (KD)        (i.e., KD (DRL));    -   the decryption key (KD) for the digital content 12 encrypted        with the black box 30 public key (PU-BB) as receive in the        license request (i.e.,(PU-BB (KD));    -   a digital signature from the license server 24 (without any        attached certificate) based on (KD (DRL)) and (PU-BB (KD)) and        encrypted with the license server 24 private key (i.e., (S        (PR-LS))); and    -   the certificate that the license server 24 obtained previously        from the content server 22, such certificate indicating that the        license server 24 has the authority from the content server 22        to issue the license 16 (i.e., (CERT (PU-LS) S (PR-CS))).        As should be understood, the aforementioned elements and perhaps        others are packaged into a digital file or some other        appropriate form. As should also be understood, if the DRL 48 or        (PU-BB (KD)) in the license 16 should become adulterated or        otherwise modified, the digital signature (S (PR-LS)) in the        license 16 will not match and therefore will not validate such        license 16. For this reason, the DRL 48 need not necessarily be        in an encrypted form (i.e., (KD(DRL)) as mentioned above),        although such encrypted form may in some instances be desirable        and therefore may be employed without departing from the spirit        and scope of the present invention.

Once the digital license 16 has been prepared, such license 16 is thenissued to the requestor (i.e., the DRM system 32 on the user's computingdevice 14) (step 719 of FIG. 7). Preferably, the license 16 istransmitted over the same path through which the request therefor wasmade (i.e., the Internet or another network), although another path maybe employed without departing from the spirit and scope of the presentinvention. Upon receipt, the requesting DRM system 32 preferablyautomatically places the received digital license 16 in the licensestore 38 (step 721).

It is to be understood that a user's computing device 14 may on occasionmalfunction, and licenses 16 stored in the license store 38 of the DRMsystem 32 on such user's computing device 14 may become irretrievablylost. Accordingly, it is preferable that the license server 24 maintaina database 50 of issued licenses 16 (FIG. 1), and that such licenseserver 24 provide a user with a copy or re-issue (hereinafter‘re-issue’) of an issued license 16 if the user is in fact entitled tosuch re-issue. In the aforementioned case where licenses 16 areirretrievably lost, it is also likely the case that state informationstored in the state store 40 and corresponding to such licenses 16 isalso lost. Such lost state information should be taken into account whenre-issuing a license 16. For example, a fixed number of renderingslicense 16 might legitimately be re-issued in a pro-rated form after arelatively short period of time, and not re-issued at all after arelatively longer period of time.

DRM System 32—Installation/Upgrade of Black Box 30

As was discussed above, as part of the function of acquiring a license16, the license server 24 may deny a request for a license 16 from auser if the user's computing device 14 has a DRM system 32 with a blackbox 30 that is not relatively current, i.e., has a relatively oldversion number. In such case, it is preferable that the black box 30 ofsuch DRM system 32 be upgraded so that the license acquisition functioncan then proceed. Of course, the black box 30 may be upgraded at othertimes without departing from the spirit and scope of the presentinvention.

Preferably, as part of the process of installing the DRM system 32 on auser's computing device 14, a non-unique ‘lite’ version of a black box30 is provided. Such ‘lite’ black box 30 is then upgraded to a uniqueregular version prior to rendering a piece of digital content 12. Asshould be understood, if each black box 30 in each DRM system 32 isunique, a security breach into one black box 30 cannot easily bereplicated with any other black box 30.

Referring now to FIG. 9, the DRM system 32 obtains the unique black box30 by requesting same from a black box server 26 or the like (as wasdiscussed above and as shown in FIG. 1) (step 901). Typically, suchrequest is made by way of the Internet, although other means of accessmay be employed without departing from the spirit and scope of thepresent invention. For example, the connection to a black box server 26may be a direct connection, either locally or remotely. An upgrade fromone unique non-lite black box 30 to another unique non-lite black box 30may also be requested by the DRM system 32 at any time, such as forexample a time when a license server 24 deems the black box 30 notcurrent, as was discussed above.

Thereafter, the black box server 26 generates a new unique black box 30(step 903). As seen in FIG. 3, each new black box 30 is provided with aversion number and a certificate with a digital signature from acertifying authority. As was discussed above in connection with thelicense acquisition function, the version number of the black box 30indicates the relative age and/or use thereof. The certificate with thedigital signature from the certifying authority, also discussed above inconnection with the license acquisition function, is a proffer orvouching mechanism from the certifying authority that a license server24 should trust the black box 30. Of course, the license server 24 musttrust the certifying authority to issue such a certificate for a blackbox 30 that is in fact trustworthy. It may be the case, in fact, thatthe license server 24 does not trust a particular certifying authority,and refuses to honor any certificate issued by such certifyingauthority. Trust may not occur, for example, if a particular certifyingauthority is found to be engaging in a pattern of improperly issuingcertificates.

Preferably, and as was discussed above, the black box server 26 includesa new unique public/private key pair (PU-BB, PR-BB) with the newlygenerated unique black box 30 (step 903 of FIG. 9). Preferably, theprivate key for the black box 30 (PR-BB) is accessible only to suchblack box 30, and is hidden from and inaccessible by the remainder ofthe world, including the computing device 14 having the DRM system 32with such black box 30, and the user thereof.

Most any hiding scheme may be employed without departing from the spiritand scope of the present invention, so long as such hiding scheme infact performs the function of hiding the private key (PR-BB) from theworld. As but one example, the private key (PR-BB) may be split intoseveral sub-components, and each sub-component may be encrypted uniquelyand stored in a different location. In such a situation, it ispreferable that such sub-components are never assembled in full toproduce the entire private key (PR-BB).

In one embodiment of the present invention, such private key (PR-BB) isencrypted according to code-based encryption techniques. In particular,in such embodiment, the actual software code of the black box 30 (orother software code) is employed as encrypting key(s). Accordingly, ifthe code of the black box 30 (or the other software code) becomesadulterated or otherwise modified, for example by a user with nefariouspurposes, such private key (PR-BB) cannot be decrypted.

Although each new black box 30 is delivered with a new public/privatekey pair (PU-BB, PR-BB), such new black box 30 is also preferably givenaccess to old public/private key pairs from old black boxes 30previously delivered to the DRM system 32 on the user's computing device14 (step 905). Accordingly, the upgraded black box 30 can still employthe old key pairs to access older digital content 12 and oldercorresponding licenses 16 that were generated according to such old keypairs, as will be discussed in more detail below.

Preferably, the upgraded black box 30 delivered by the black box server26 is tightly tied to or associated with the user's computing device 14.Accordingly, the upgraded black box 30 cannot be operably transferredamong multiple computing devices 14 for nefarious purposes or otherwise.In one embodiment of the present invention, as part of the request forthe black box 30 (step 901) the DRM system 32 provides hardwareinformation unique to such DRM system 32 and/or unique to the user'scomputing device 14 to the black box server 26, and the black box server26 generates a black box 30 for the DRM system 32 based in part on suchprovided hardware information. Such generated upgraded black box 30 isthen delivered to and installed in the DRM system 32 on the user'scomputing device 14 (steps 907, 909). If the upgraded black box 30 isthen somehow transferred to another computing device 14, the transferredblack box 30 recognizes that it is not intended for such other computingdevice 14, and does not allow any requested rendering to proceed on suchother computing device 14.

Once the new black box 30 is installed in the DRM system 32, such DRMsystem 32 can proceed with a license acquisition function or with anyother function.

DRM System 32—Content Rendering Part 3

Referring now to FIG. 5B, and assuming, now, that the license evaluator36 has found at least one valid license 16 and that at least one of suchvalid licenses 16 provides the user with the rights necessary to renderthe corresponding digital content 12 in the manner sought (i.e., isenabling), the license evaluator 36 then selects one of such licenses 16for further use (step 519). Specifically, to render the requesteddigital content 12, the license evaluator 36 and the black box 30 incombination obtain the decryption key (KD) from such license 16, and theblack box 30 employs such decryption key (KD) to decrypt the digitalcontent 12. In one embodiment of the present invention, and as wasdiscussed above, the decryption key (KD) as obtained from the license 16is encrypted with the black box 30 public key (PU-BB(KD)), and the blackbox 30 decrypts such encrypted decryption key with its private key(PR-BB) to produce the decryption key (KD) (steps 521, 523). However,other methods of obtaining the decryption key (KD) for the digitalcontent 12 may be employed without departing from the spirit and scopeof the present invention.

Once the black box 30 has the decryption key (KD) for the digitalcontent 12 and permission from the license evaluator 36 to render thedigital content 12, control may be returned to the rendering application34 (steps 525, 527). In one embodiment of the present invention, therendering application 34 then calls the DRM system 32/black box 30 anddirects at least a portion of the encrypted digital content 12 to theblack box 30 for decryption according to the decryption key (KD) (step529). The black box 30 decrypts the digital content 12 based upon thedecryption key (KD) for the digital content 12, and then the black box30 returns the decrypted digital content 12 to the rendering application34 for actual rendering (steps 533, 535). The rendering application 34may either send a portion of the encrypted digital content 12 or theentire digital content 12 to the black box 30 for decryption based onthe decryption key (KD) for such digital content 12 without departingfrom the spirit and scope of the present invention.

Preferably, when the rendering application 34 sends digital content 12to the black box 30 for decryption, the black box 30 and/or the DRMsystem 32 authenticates such rendering application 34 to ensure that itis in fact the same rendering application 34 that initially requestedthe DRM system 32 to run (step 531). Otherwise, the potential existsthat rendering approval may be obtained improperly by basing therendering request on one type of rendering application 34 and in factrendering with another type of rendering application 34. Assuming theauthentication is successful and the digital content 12 is decrypted bythe black box 0.30, the rendering application 34 may then render thedecrypted digital content 12 (steps 533, 535).

Sequence of Key Transactions

Referring now to FIG. 10, in one embodiment of the present invention, asequence of key transactions is performed to obtain the decryption key(KD) and evaluate a license 16 for a requested piece of digital content12 (i.e., to perform steps 515-523 of FIGS. 5A and 5B). Mainly, in suchsequence, the DRM system 32 obtains the decryption key (KD) from thelicense 16, uses information obtained from the license 16 and thedigital content 12 to authenticate or ensure the validity of both, andthen determines whether the license 16 in fact provides the right torender the digital content 12 in the manner sought. If so, the digitalcontent 12 may be rendered.

Bearing in mind that each license 16 for the digital content 12, as seenin FIG. 8, includes:

-   -   the content ID of the digital content 12 to which the license 16        applies;    -   the Digital Rights License (DRL) 48, perhaps encrypted with the        decryption key (KD) (i.e., KD (DRL));    -   the decryption key (KD) for the digital content 12 encrypted        with the black box 30 public key (PU-BB) (i.e.,(PU-BB (KD));    -   the digital signature from the license server 24 based on (KD        (DRL)) and (PU-BB (KD)) and encrypted with the license server 24        private key (i.e., (S (PR-LS))); and    -   the certificate that the license server 24 obtained previously        from the content server 22 (i.e., (CERT (PU-LS) S (PR-CS))),        and also bearing in mind that the package 12 p having the        digital content 12, as seen in FIG. 3, includes:    -   the content ID of such digital content 12;    -   the digital content 12 encrypted by KD (i.e., (KD(CONTENT)));    -   a license acquisition script that is not encrypted; and    -   the key KD encrypting the content server 22 public key (PU-CS),        signed by the content server 22 private key (PR-CS) (i.e., (KD        (PU-CS) S (PR-CS))), in one embodiment of the present invention,        the specific sequence of key transactions that are performed        with regard to a specific one of the licenses 16 for the digital        content 12 is as follows:

1. Based on (PU-BB (KD)) from the license 16, the black box 30 of theDRM system 32 on the user's computing device 14 applies its private key(PR-BB) to obtain (KD) (step 1001). (PR-BB (PU-BB (KD))=(KD)). Note,importantly, that the black box 30 could then proceed to employ KD todecrypt the digital content 12 without any further ado. However, andalso importantly, the license server 24 trusts the black box 30 not todo so. Such trust was established at the time such license server 24issued the license 16 based on the certificate from the certifyingauthority vouching for the trustworthiness of such black box 30.Accordingly, despite the black box 30 obtaining the decryption key (KD)as an initial step rather than a final step, the DRM system 32 continuesto perform all license 16 validation and evaluation functions, asdescribed below.

2. Based on (KD (PU-CS) S (PR-CS)) from the digital content 12, theblack box 30 applies the newly obtained decryption key (KD) to obtain(PU-CS) (step 1003). (KD (KD (PU-CS))=(PU-CS)). Additionally, the blackbox 30 can apply (PU-CS) as against the signature (S (PR-CS)) to satisfyitself that such signature and such digital content 12/package 12 p isvalid (step 1005). If not valid, the process is halted and access to thedigital content 12 is denied.

3. Based on (CERT (PU-LS) S (PR-CS)) from the license 16, the black box30 applies the newly obtained content server 22 public key (PU-CS) tosatisfy itself that the certificate is valid (step 1007), signifyingthat the license server 24 that issued the license 16 had the authorityfrom the content server 22 to do so, and then examines the certificatecontents to obtain (PU-LS) (step 1009). If not valid, the process ishalted and access to the digital content 12 based on the license 16 isdenied.

4. Based on (S (PR-LS)) from the license 16, the black box 30 appliesthe newly obtained license server 24 public key (PU-LS) to satisfyitself that the license 16 is valid (step 0111). If not valid, theprocess is halted and access to the digital content 12 based on thelicense 16 is denied.

5. Assuming all validation steps are successful, and that the DRL 48 inthe license 16 is in fact encrypted with the decryption key (KD), thelicense evaluator 36 then applies the already-obtained decryption key(KD) to (KD(DRL)) as obtained from the license 16 to obtain the licenseterms from the license 16 (i.e., the DRL 48) (step 1013). Of course, ifthe DRL 48 in the license 16 is not in fact encrypted with thedecryption key (KD), step 1013 may be omitted. The license evaluator 36then evaluates/interrogates the DRL 48 and determines whether the user'scomputing device 14 has the right based on the DRL 48 in the license 16to render the corresponding digital content 12 in the manner sought(i.e., whether the DRL 48 is enabling) (step 1015). If the licenseevaluator 36 determines that such right does not exist, the process ishalted and access to the digital content 12 based on the license 16 isdenied.

6. Finally, assuming evaluation of the license 16 results in a positivedetermination that the user's computing device 14 has the right based onthe DRL 48 terms to render the corresponding digital content 12 in themanner sought, the license evaluator 36 informs the black box 30 thatsuch black box 30 can render the corresponding digital content 12according to the decryption key (KD). The black box 30 thereafterapplies the decryption key (KD) to decrypt the digital content 12 fromthe package 12 p (i.e., (KD(KD(CONTENT))=(CONTENT)) (step 1017).

It is important to note that the above-specified series of stepsrepresents an alternating or ‘ping-ponging’ between the license 16 andthe digital content 12. Such ping-ponging ensures that the digitalcontent 12 is tightly bound to the license 16, in that the validationand evaluation process can only occur if both the digital content 12 andlicense 16 are present in a properly issued and valid form. In addition,since the same decryption key (KD) is needed to get the content server22 public key (PU-CS) from the license 16 and the digital content 12from the package 12 p in a decrypted form (and perhaps the license terms(DRL 48) from the license 16 in a decrypted form), such items are alsotightly bound. Signature validation also ensures that the digitalcontent 12 and the license 16 are in the same form as issued from thecontent server 22 and the license server 24, respectively. Accordingly,it is difficult if not impossible to decrypt the digital content 12 bybypassing the license server 24, and also difficult if not impossible toalter and then decrypt the digital content 12 or the license 16.

In one embodiment of the present invention, signature verification, andespecially signature verification of the license 16, is alternatelyperformed as follows. Rather than having a signature encrypted by theprivate key of the license server 16 (PR-LS), as is seen in FIG. 8, eachlicense 16 has a signature encrypted by a private root key (PR-R) (notshown), where the black box 30 of each DRM system 32 includes a publicroot key (PU-R) (also not shown) corresponding to the private root key(PR-R). The private root key (PR-R) is known only to a root entity, anda license server 24 can only issue licenses 16 if such license server 24has arranged with the root entity to issue licenses 16.

In particular, in such embodiment:

-   -   1. the license server 24 provides its public key (PU-LS) to the        root entity;    -   2. the root entity returns the license server public key (PU-LS)        to such license server 24 encrypted with the private root key        (PR-R) (i.e., (CERT (PU-LS) S (PR-R))); and    -   3. the license server 24 then issues a license 16 with a        signature encrypted with the license server private key (S        (PR-LS)), and also attaches to the license the certificate from        the root entity (CERT (PU-LS) S (PR-R)).

For a DRM system 18 to validate such issued license 16, then, the DRMsystem 18:

-   -   1. applies the public root key (PU-R) to the attached        certificate (CERT (PU-LS) S (PR-R)) to obtain the license server        public key (PU-LS); and    -   2. applies the obtained license server public key (PU-LS) to the        signature of the license 16 (S (PR-LS).

Importantly, it should be recognized that just as the root entity gavethe license server 24 permission to issue licenses 16 by providing thecertificate (CERT (PU-LS) S (PR-R)) to such license server 24, suchlicense server 24 can provide a similar certificate to a second licenseserver 24 (i.e., (CERT (PU-LS2) S (PR-LS1)), thereby allowing the secondlicense server to also issue licenses 16. As should now be evident, alicense 16 issued by the second license server would include a firstcertificate (CERT (PU-LS1) S (PR-R)) and a second certificate (CERT(PU-LS2) S (PR-LS1)). Likewise, such license 16 is validated byfollowing the chain through the first and second certificates. Ofcourse, additional links in the chain may be added and traversed.

One advantage of the aforementioned signature verification process isthat the root entity may periodically change the private root key(PR-R), thereby likewise periodically requiring each license server 24to obtain a new certificate (CERT (PU-LS) S (PR-R)). Importantly, as arequirement for obtaining such new certificate, each license server maybe required to upgrade itself. As with the black box 30, if a licenseserver 24 is relatively current, i.e., has been upgraded relativelyrecently, it is less likely that license server 24 has been successfullyattacked. Accordingly, as a matter of trust, each license server 24 ispreferably required to be upgraded periodically via an appropriateupgrade trigger mechanism such as the signature verification process. Ofcourse, other upgrade mechanisms may be employed without departing fromthe spirit and scope of the present invention.

Of course, if the private root key (PR-R) is changed, then the publicroot key (PU-R) in each DRM system 18 must also be changed. Such changemay for example take place during a normal black box 30 upgrade, or infact may require that a black box 30 upgrade take place. Although achanged public root key (PU-R) may potentially interfere with signaturevalidation for an older license 16 issued based on an older private rootkey (PR-R), such interference may be minimized by requiring that anupgraded black box 30 remember all old public root keys (PU-R).Alternatively, such interference may be minimized by requiring signatureverification for a license 16 only once, for example the first time suchlicense 16 is evaluated by the license evaluator 36 of a DRM system 18.In such case, state information on whether signature verification hastaken place should be compiled, and such state information should bestored in the state store 40 of the DRM system 18.

Digital Rights License 48

In the present invention, the license evaluator 36 evaluates a DigitalRights License (DRL) 48 as the rights description or terms of a license16 to determine if such DRL 48 allows rendering of a corresponding pieceof digital content 12 in the manner sought. In one embodiment of thepresent invention, the DRL 48 may be written by a licensor (i.e., thecontent owner) in any DRL language.

As should be understood, there are a multitude of ways to specify a DRL48. Accordingly, a high degree of flexibility must be allowed for in anyDRL language. However, it is impractical to specify all aspects of a DRL48 in a particular license language, and it is highly unlikely that theauthor of such a language can appreciate all possible licensing aspectsthat a particular digital licensor may desire. Moreover, a highlysophisticated license language may be unnecessary and even a hindrancefor a licensor providing a relatively simple DRL 48. Nevertheless, alicensor should not be unnecessarily restricted in how to specify a DRL48. At the same time, the license evaluator 36 should always be able toget answers from a DRL 48 regarding a number of specific licensequestions.

In the present invention, and referring now to FIG. 11, a DRL 48 can bespecified in any license language, but includes a language identifier ortag 54. The license evaluator 36 evaluating the license 16, then,performs the preliminary step of reviewing the language tag 54 toidentify such language, and then selects an appropriate license languageengine 52 for accessing the license 16 in such identified language. Asshould be understood, such license language engine 52 must be presentand accessible to the license evaluator 36. If not present, the languagetag 54 and/or the DRL 48 preferably includes a location 56 (typically aweb site) for obtaining such language engine 52.

Typically, the language engine 52 is in the form of an executable fileor set of files that reside in a memory of the user's computing device14, such as a hard drive. The language engine 52 assists the licenseevaluator 36 to directly interrogate the DRL 48, the license evaluator36 interrogates the DRL 48 indirectly via the language engine 48 actingas an intermediary, or the like. When executed, the language engine 52runs in a work space in a memory of the user's computing device 14, suchas RAM. However, any other form of language engine 52 may be employedwithout departing from the spirit and scope of the present invention.

Preferably, any language engine 52 and any DRL language supports atleast a number of specific license questions that the license evaluator36 expects to be answered by any DRL 48, as will be discussed below.Accordingly, the license evaluator 36 is not tied to any particular DRLlanguage; a DRL 48 may be written in any appropriate DRL language; and aDRL 48 specified in a new license language can be employed by anexisting license evaluator 36 by having such license evaluator 36 obtaina corresponding new language engine 52.

DRL Languages

Two examples of DRL languages, as embodied in respective DRLs 48, areprovided below. The first, ‘simple’ DRL 48 is written in a DRL languagethat specifies license attributes, while the second ‘script’ DRL 48 iswritten in a DRL language that can perform functions according to thescript specified in the DRL 48. While written in a DRL language, themeaning of each line of code should be apparent based on the linguisticsthereof and/or on the attribute description chart that follows:

Simple DRL 48: <LICENSE>  <DATA>   <NAME>Beastie Boy's Play</NAME>  <ID>39384</ID>   <DESCRIPTION>Play the song 3 times</DESCRIPTION>  <TERMS></TERMS>   <VALIDITY>    <NOTBEFORE>1998010223:20:14Z</NOTBEFORE>    <NOTAFTER>19980102 23:20:14Z</NOTAFTER>  </VALIDITY>   <ISSUEDDATE>19980102 23:20:14Z</ISSUEDDATE>  <LICENSORSITE>http://www.foo.com</LICENSORSITE>   <CONTENT>   <NAME>Beastie Boy's</NAME>    <ID>392</ID>    <KEYID>39292</KEYID>   <TYPE>MS Encrypted ASF 2.0</TTYPE>   </CONTENT>   <OWNER>   <ID>939KDKD393KD</ID>    <NAME>Universal</NAME>   <PUBLICKEY></PUBLICKEY>   </OWNER>   <LICENSEE>   <NAME>Arnold</NAME>    <ID>939KDKD393KD</ID>   <PUBLICKEY></PUBLICKEY>   </LICENSEE>   <PRINCIPAL TYPE=‘AND’>   <PRINCIPAL TYPE=‘OR’>     <PRINCIPAL>      <TYPE>x86Computer</TYPE>     <ID>3939292939d9e939</ID>      <NAME>Personal Computer</NAME>     <AUTHTYPE>Intel Authenticated Boot PC SHA-1      DSA512</AUTHTYPE>     <AUTHDATA>29293939</AUTHDATA>     </PRINCIPAL>     <PRINCIPAL>     <TYPE>Application</TYPE>      <ID>2939495939292</ID>     <NAME>Window's Media Player</NAME>      <AUTHTYPE>Authenticode SHA-     1</AUTHTYPE>      <AUTHDATA>93939</AUTHDATA>     </PRINCIPAL>   </PRINCIPAL>    <PRINCIPAL>     <TYPE>Person</TYPE>    <ID>39299482010</ID>     <NAME>Arnold Blinn</NAME>    <AUTHTYPE>Authenticate user</AUTHTYPE>    <AUTHDATA>\\redmond\arnoldb</AUTHDATA>    </PRINCIPAL>  </PRINCIPAL>   <DRLTYPE>Simple</DRLTYPE> [the language tag 54]  <DRLDATA>    <START>19980102 23:20:14Z</START>    <END>1998010223:20:14Z</END>    <COUNT>3</COUNT>    <ACTION>PLAY</ACTION>  </DRLDATA>   <ENABLINGBITS>aaaabbbbccccdddd</ENABLINGBITS>  </DATA> <SIGNATURE>  <SIGNERNAME>Universal</SIGNERNAME>  <SIGNERID>9382ABK3939DKD</SIGNERID>  <HASHALGORITHMID>MD5</HASHALGORITHMID>   <SIGNALGORITHMID>RSA128</SIGNALGORITHMID>   <SIGNATURE>xxxyyyxxxyyyxxxyyy</SIGNATURE>  <SIGNERPUBLICKEY></SIGNERPUBLICKEY>   <CONTENTSIGNEDSIGNERPUBLICKEY></  CONTENTSIGNEDSIGNERPUBLICKEY>  </SIGNATURE> </LICENSE> Script DRL 48:<LICENSE>  <DATA>   <NAME>Beastie Boy's Play</NAME>   <ID>39384</ID>  <DESCRIPTION>Play the song unlimited</DESCRIPTION>   <TERMS></TERMS>  <VALIDITY>    <NOTBEFORE>19980102 23:20:14Z</NOTBEFORE>   <NOTAFTER>19980102 23:20:14Z</NOTAFTER>   </VALIDITY>  <ISSUEDDATE>19980102 23:20:14Z</ISSUEDDATE>  <LICENSORSITE>http://www.foo.com</LICENSORSITE>   <CONTENT>   <NAME>Beastie Boy's</NAME    <ID>392</ID>    <KEYID>39292</KEYID>   <TYPE>MS Encrypted ASF 2.0</TTYPE>   </CONTENT>   <OWNER>   <ID>939KDKD393KD</ID>    <NAME>Universal</NAME>   <PUBLICKEY></PUBLICKEY>   </OWNER>   <LICENSEE>   <NAME>Arnold</NAME>    <ID>939KDKD393KD</ID>   <PUBLICKEY></PUBLICKEY>   </LICENSEE>  <DRLTYPE>Script</DRLTYPE> [the language tag 54]   <DRLDATA>   function on_enable(action, args) as boolean     result = False     ifaction = “PLAY” then      result = True     end if     on_action = False   end function    ...   </DRLDATA>  </DATA>  <SIGNATURE>  <SIGNERNAME>Universal</SIGNERNAME>   <SIGNERID>9382</SIGNERID>  <SIGNERPUBLICKEY></SIGNERPUBLICKEY>   <HASHID>MD5</HASHID>  <SIGNID>RSA 128</SIGNID>   <SIGNATURE>xxxyyyxxxyyyxxxyyy</SIGNATURE>  <CONTENTSIGNEDSIGNERPUBLICKEY></   CONTENTSIGNEDSIGNERPUBLICKEY> </SIGNATURE> </LICENSE>

In the two DRLs 48 specified above, the attributes listed have thefollowing descriptions and data types: Attribute Description Data TypeId ID of the license GUID Name Name of the license String Content Id IDof the content GUID Content Key Id ID for the encryption key of thecontent GUID Content Name Name of the content String Content Type Typeof the content String Owner Id ID of the owner of the content GUID OwnerName Name of the owner of the content String Owner Public Key Public keyfor owner of content. This String is a base-64 encoded public key forthe owner of the content. Licensee Id Id of the person getting license.It may GUID be null. Licensee Name Name of the person getting license.It String may be null. Licensee Public Key Public key of the licensee.This is the String base-64 encoded public key of the licensee. It may benull. Description Simple human readable description of String thelicense Terms Legal terms of the license. This may be String a pointerto a web page containing legal prose. Validity Not After Validity periodof license expiration Date Validity Not Before Validity period oflicense start Date Issued Date Date the license was issued Date DRL TypeType of the DRL. Example include String “SIMPLE” or “SCRIPT” DRL DataData specific to the DRL String Enabling Bits These are the bits thatenable access to String the actual content. The interpretation of thesebits is up to the application, but typically this will be the privatekey for decryption of the content. This data will be base-64 encoded.Note that these bits are encrypted using the public key of theindividual machine. Signer Id ID of person signing license GUID SignerName Name of person signing license String Signer Public Key Public keyfor person signing license. String This is the base-64 encode public keyfor the signer. Content Signed Signer Public Public key for personsigning the String Key license that has been signed by the contentserver private key. The public key to verify this signature will beencrypted in the content. This is base- 64 encoded. Hash Alg IdAlgorithm used to generate hash. This String is a string, such as “MD5”.Signature Alg Id Algorithm used to generate signature. String This is astring, such as “RSA 128”. Signature Signature of the data. This isbase-64 String encoded data.Methods

As was discussed above, it is preferable that any language engine 52 andany DRL language support at least a number of specific license questionsthat the digital license evaluator 36 expects to be answered by any DRL48. Recognizing such supported questions may include any questionswithout departing from the spirit and scope of the present invention,and consistent with the terminology employed in the two DRL 48 examplesabove, in one embodiment of the present invention, such supportedquestions or ‘methods’ include ‘access methods’, ‘DRL methods’, and‘enabling use methods’, as follows:

Access Methods

Access methods are used to query a DRL 48 for top-level attributes.

VARIANT QueryAttribute (BSTR Key)

Valid keys include License.Name, License.Id, Content.Name, Content.Id,Content.Type, Owner.Name, Owner.Id, Owner.PublicKey, Licensee.Name,Licensee.Id, Licensee.PublicKey, Description, and Terms, each returninga BSTR variant; and Issued, Validity.Start and Validity.End, eachreturning a Date Variant.

DRL Methods

The implementation of the following DRL methods varies from DRL 48 toDRL 48. Many of the DRL methods contain a variant parameter labeled‘data’ which is intended for communicating more advanced informationwith a DRL 48. It is present largely for future expandability.

Boolean IsActivated(Variant Data)

This method returns a Boolean indicating whether the DRL 48/license 16is activated.

An example of an activated license 16 is a limited operation license 16that upon first play is active for only 48 hours.

Activate(Variant Data)

This method is used to activate a license 16. Once a license 16 isactivated, it cannot be deactivated.

Variant QueryDRL(Variant Data)

This method is used to communicate with a more advanced DRL 48. It islargely about future expandability of the DRL 48 feature set.

Variant GetExpires(BSTR Action, Variant Data)

This method returns the expiration date of a license 16 with regard tothe passed-in action. If the return value is NULL, the license 16 isassumed to never expire or does not yet have an expiration date becauseit hasn't been activated, or the like.

Variant GetCount(BSTR Action, Variant Data)

This method returns the number of operations of the passed-in actionthat are left. If NULL is returned, the operation can be performed anunlimited number of times.

Boolean IsEnabled(BSTR Action, Variant Data)

This method indicates whether the license 16 supports the requestedaction at the present time.

Boolean IsSunk(BSTR Action, Variant Data)

This method indicates whether the license 16 has been paid for. Alicense 16 that is paid for up front would return TRUE, while a license16 that is not paid for up front, such as a license 16 that collectspayments as it is used, would return FALSE.

Enabling Use Methods.

These methods are employed to enable a license 16 for use in decryptingcontent.

Boolean Validate (BSTR Key)

This method is used to validate a license 16. The passed-in key is theblack box 30 public key (PU-BB) encrypted by the decryption key (KD) forthe corresponding digital content 12 (i.e.,(KD(PU-BB))) for use invalidation of the signature of the license 16. A return value of TRUEindicates that the license 16 is valid. A return value of FALSEindicates invalid.

int OpenLicense 16(BSTR Action, BSTR Key, Variant Data)

This method is used to get ready to access the decrypted enabling bits.The passed-in key is (KD(PU-BB)) as described above. A return value of 0indicates success. Other return values can be defined.

BSTR GetDecryptedEnablingBits (BSTR Action, Variant Data)

Variant GetDecryptedEnablingBitsAsBinary (BSTR Action, Variant Data)

These methods are used to access the enabling bits in decrypted form. Ifthis is not successful for any of a number of reasons, a null string ornull variant is returned.

void CloseLicense (BSTR Action, Variant Data)

This method is used to unlock access to the enabling bits for performingthe passed-in action. If this is not successful for any of a number ofreasons, a null string is returned.

Heuristics

As was discussed above, if multiple licenses 16 are present for the samepiece of digital content 12, one of the licenses 16 must be chosen forfurther use. Using the above methods, the following heuristics could beimplemented to make such choice. In particular, to perform an action(say “PLAY”) on a piece of digital content 12, the following steps couldbe performed:

1. Get all licenses 16 that apply to the particular piece of digitalcontent 12.

2. Eliminate each license 16 that does not enable the action by callingthe IsEnabled function on such license 16.

3. Eliminate each license 16 that is not active by calling IsActivatedon such license 16.

4. Eliminate each license 16 that is not paid for up front by callingIsSunk on such license 16.

5. If any license 16 is left, use it. Use an unlimited-number-of-playslicense 16 before using a limited-number-of-plays license 16, especiallyif the unlimited-number-of-plays license 16 has an expiration date. Atany time, the user should be allowed to select a specific license 16that has already been acquired, even if the choice is notcost-effective. Accordingly, the user can select a license 16 based oncriteria that are perhaps not apparent to the DRM system 32.

6. If there are no licenses 16 left, return status so indicating. Theuser would then be given the option of:

-   -   using a license 16 that is not paid for up front, if available;    -   activating a license 16, if available; and/or performing license        acquisition from a license server 24.        Further Concepts—Path Authentication

As was set forth above, when the rendering application 34 sends digitalcontent 12 to the black box 30 for decryption, the black box 30 and/orthe DRM system 32 preferably authenticates that such renderingapplication 34 is in fact the same rendering application 34 thatinitially requested the DRM system 32 to run (step 531 of FIG. 5) andthat the rendering application 34 itself satisfies any relevant terms inthe corresponding digital license 16. In addition, such authenticationensures that such rendering application 34 can be trusted to handle thedecrypted or ‘naked’ digital content 12 in an appropriate manner, andalso that the rendering application 34 can be trusted to handle othersensitive matter (i.e., keys, encrypted matter, and/or other trustedmatter). However, and referring now to FIG. 13, it is to be recognizedthat the digital content 12 likely will ‘flow’ in a path 58 from therendering application 34 to an ultimate destination 60 by way of one ormore modules 62 that define such path 58.

As should be appreciated, the path 58 may be any path without departingfrom the spirit and scope of the present invention. For example, thepath 58 may include multiple branches, junctions, loops, and the like.Likewise, the modules 62 may be any modules without departing from thespirit and scope of the present invention, and can include softwaremodules and hardware modules including software. For example, foraudio-based digital content 12, the modules 62 may include modulesperforming noise reduction, equalization, balance, and frequencyfiltering functions, among others. Correspondingly, for multimedia-baseddigital content 12, the modules 62 may include the aforementionedaudio-function modules as well as various video-function modules,synchronization modules, and the like. Of course, the ultimatedestination 60 will vary based on the digital content 12, but likelyincludes one or more audio output devices (a sound card, e.g.), one ormore video output devices (a video card, e.g.), or the like.

It is to be recognized that the rendering application 34 itself may havemany aspects of a path such as the path 58. In particular, and dependingupon the particular rendering application 34, such application 34 may beinstantiated in the form of several modules 62 defining the flow ofdigital content 12 therethrough. Therefore, it can at times be difficultto define where the rendering application 24 ends and where the path 58begins. Nevertheless, for purposes of the present invention and thepresent disclosure, where the rendering application 24 ends and wherethe path 58 begins can be arbitrarily defined at any appropriate pointif need be without departing from the spirit and scope of the presentinvention. In fact, the rendering application 34 can include at least aportion of the path 58, if not the entirety thereof, and the path 58 caninclude at least a portion of the rendering application 34, if not theentirety thereof, without departing from the spirit and scope of thepresent invention.

Thus, the black box 30 and/or the DRM system 32 also preferablyauthenticates such path 58 to ensure that each constituent module 62 inthe path 58 is to be trusted by the DRM system 32. Otherwise, thepotential exists that one or modules 62 in the path can be employed by anefarious entity to obtain the naked digital content 12 as such nakeddigital content 12 leaves the rendering application 34. Assuming thepath authentication is successful, the digital content 12 may then bedecrypted by the black box 30 and forwarded to the rendering application34 for further forwarding down the path 58 to the ultimate destination60.

As is to be understood, and as shown in FIG. 13, the path 58 typicallyincludes a user mode portion 58 u and a kernel portion 58 k. The usermode portion 58 u encompasses modules 62 that reside in a user portion14 u of the user's computing device 14, and includes functionality morespecific to the user and the rendering application 34. Correspondingly,the kernel portion 58 k encompasses modules 62 that reside in a kernelportion 14 k of the user's computing device 14 and includesfunctionality more specific to the core operations of the user'scomputing device 14. As seen, each portion 58 u, 58 k may includebranches, junctions, loops, and the like.

In one embodiment of the present invention, and referring now to FIG.14, the DRM system 32 directs the rendering application 14 to outputnaked digital content 12 in a scrambled form such that the scrambleddigital content 12 enters the user mode portion 58 u of the path 58(step 1401). Such scrambled digital content 12 is then acted upon and/orvariously manipulated by the various modules 62 that define the usermode portion 58 u of the path 58, and the resulting scrambledmanipulated digital content 12 transits from the user mode portion 58 uto the kernel portion 58 k of the path 58 (step 1403). Importantly, theDRM system 32 also directs that upon leaving the user mode portion 58u/entering the kernel portion 58 k, the scrambled manipulated digitalcontent 12 is de-scrambled by an appropriate de-scrambling module 62,preferably in the kernel portion 58 k of the path 58 (step 1405).

As may be appreciated, such scrambling and de-scrambling can take anyappropriate form without departing from the spirit and scope of thepresent invention. Of course the scrambling and de-scrambling elementsmust agree beforehand on the form and all necessary protocols. Forexample, appropriate encryption and decryption techniques may beemployed based on a symmetric or asymmetric key. As may also beappreciated, by presenting scrambled digital content 12 to each module62 in the user mode portion 58 u of the path 58, each such module 62 isessentially prevented from performing any operations on such scrambleddigital content 12. Thus, the user mode portion 58 u of the path 58 isessentially omitted or ‘tunneled’, whereby none of the modules 62 insuch user mode portion 58 u is allowed to manipulate the digital content12 as it passes through such portion 58 u of the path 58. Nevertheless,such tunneling is not considered to be especially problematic in thatthe kernel portion 58 k of the path 58 typically replicates most of thefunctions performed in the user mode portion 58 u.

In such embodiment, the digital content 12 is de-scrambled (i.e., againnaked) in the kernel portion 58 k of the path because each module insuch kernel portion 58 k that is in contact with/can manipulate/can‘touch’ the naked digital content 12 has already authenticated itself tothe DRM system 32. Specifically, prior to releasing the digital content12 to the rendering application 34 and beyond, the DRM system 32performs a traversal of the kernel portion 58 k of the path 58 to ineffect develop a map of each module in the path 58 and authenticate eachpath module 62. That is, recognizing that the kernel portion 14 k of theuser's computing device 14 comprises many modules 62, only a few ofwhich actually define the kernel portion 58 k of the path 58, the DRMsystem 32 seeks to discover and authenticate each such path-definingmodule 62. Correspondingly, the DRM system 32 does not bother todiscover and authenticate other modules 62 that do not define the path58 and therefore would not touch the naked digital content 12.

In one embodiment of the present invention, and referring now to FIG. 15the DRM system 32 performs such traversal and authentication by startingat an initial module 62 in the kernel portion 58 k of the path andauthenticating such initial module 62 (step 1501), determining allpossible destination modules 62 that receive data from such initialmodule 62 (step 1503), going to each possible destination module 62 andauthenticating each such destination module 62 (step 1505), determiningall possible destination modules 62 that receive data from suchdestination module 62 (step 1507), etc., and iteratively repeating suchsteps until the map of the kernel portion 58 k of the path is fullydefined and each module 62 in such kernel portion 58 k has beenauthenticated (step 1509). Of course, determining all possibledestinations from each module 62 may be done by appropriate examinationof such module 62; such module may even include an explicit destinationlist.

In one embodiment of the present invention, the DRM system 32authenticates each module 62 by querying the module 62 for the path andfile name of the executable file from which such module 62 arose (i.e.,on a hard drive, a server, etc.), and the memory address for the module62 as it resides in dynamic memory (i.e., RAM or the like). The DRMsystem 32 then locates the executable file, finds therein a signature,and checks such signature to ensure the executable file was not tamperedwith, among other things. The DRM system 32 then locates the module 62as it resides in dynamic memory and checks to ensure that such module 62as it resides in dynamic memory does not materially differ from theexecutable file to ensure that the module 62 as it resides in dynamicmemory was not tampered with, among other things. In addition, the DRMsystem 32 can look in the module 62 as it resides in dynamic memory tofind all destination modules 62 arrived at from such module 62. As maybe appreciated, such destination modules 62 may be explicitly stated ormay be discerned relatively simply by looking for calls or the like.

The aforementioned initial module 62 should be the first module thatsees the naked digital content 12 in the kernel portion 14 k, and thusis likely to be the aforementioned de-scrambling module 62. However,other modules 62 may be the first module that sees the naked digitalcontent 12 without departing from the spirit and scope of the presentinvention, and other modules 62 other than such first module may be theinitial module 62, again without departing from the spirit and scope ofthe present invention. However, such initial module 62 should be chosento be a module that will lead to fully discovering all other modules 62that define the kernel portion 58 k of the path 58.

The DRM system 32 may employ an appropriate database device to keeptrack of all modules 62 determined to be in the kernel portion 58 k ofthe path 58, all modules 62 authenticated, etc. Accordingly, such DRMsystem 32 can for example recognize when a loop in such path 58 has beenencountered, and can avoid endless re-authentication of each module 62in the loop. The particular sequence of determining and authenticatingmodules 62 may vary without departing from the spirit and scope of thepresent invention. For example, modules 62 may be authenticated asdetermined in the manner set forth above, all modules 62 may bedetermined first and then authenticated, or a combination thereof.

In one embodiment of the present invention, each path module 62authenticates itself by proffering to the DRM system 32 upon request aproper certificate 64 (FIG. 13) as received from a certifying authority.Such certificate 64 may be any appropriate certificate as received froman approved certifying authority without departing from the spirit andscope of the present invention. For example, the certificate 64 mayinclude a hash of the module 62 as a verifying feature, or may include apublic key for decrypting an attached verifying message. Of course, eachmodule 62 in the kernel portion 58 k of the path 58 must already havesuch a certificate 64, or else such module 62 cannot be authenticated.The DRM system 32 reviews the proffered certificate 64 upon receipt fromthe module 62 and determines if the received certificate 64 isacceptable for purposes of authenticating the module 62.

If even a single module 62 in the kernel portion 58 k of the path 58fails to authenticate itself to the satisfaction of the DRM system 32,and the corresponding license 16 is silent on the subject, such DRMsystem 32 declares the path 58 suspect and refuses to release thedigital content 12 to the rendering application 34 and beyond (steps1511, 1513). Correspondingly, if all modules 62 in the kernel portion 58k of the path 58 succeed in authenticating themselves to thesatisfaction of the DRM system 32, such DRM system 32 declares the path58 trustworthy and allows the digital content 12 to be released to therendering application 34 and beyond, subject to any and all otherrequirements having been met (steps 1511, 1515). In the case whereauthentication is performed as each module 62 is determined and a module62 fails to authenticate itself, the traversal may be completed if forexample a need exists to fully define the map of the path 58, or thetraversal may be stopped without further determination of modules 62 inthe path 58.

As an alternative, and as was alluded to above, the correspondinglicense 16 may include explicit instructions as to what to do if amodule 62 in the path 58 fails to authenticate itself. Of course, suchinstructions may vary in any manner without departing from the spiritand scope of the present invention. For example, the license 16 mayallow a certain number of non-authenticating modules 62 in the path 58,or may include a function describing when to declare the path 58suspect, or may even allow for any and all non-authenticating modules62. As another alternative, in the absence of explicit instructions inthe corresponding license 16, the DRM system 32 may include defaultinstructions. Again, such instructions may vary in any manner withoutdeparting from the spirit and scope of the present invention.

As described above, the DRM system 32 performs the work ofauthenticating each module 62. However, in an alternate embodiment ofthe present invention, each module 62 in the path 58 performs the workof authenticating the next module(s) 62 in the path. Note that eachmodule 62 authenticating the next module(s) 62 should be a relativelysimple task inasmuch as each module 62 should already have intimateknowledge of exactly which module(s) 62 are in fact the next module(s)62. Thus, the task of authentication is de-centralized, and may beperformed on an on-going basis as needed.

In one embodiment of the present invention, recognizing that somemanipulating of the digital content 12 should be performed by modules inthe user mode portion 58 u of the path, certain types of scrambling maybe performed that both protect the digital content 12 and allow suchmanipulation to take place. For example, if scrambling is performed ononly a less significant portion of each piece of the digital content 12(the less significant byte of each 2-byte piece of data, e.g.), certaintypes of manipulating could be performed on such digital content 12 evenin the scrambled form.

In one embodiment of the present invention, recognizing that somesituations require full manipulation of the digital content 12 bymodules 62 in the user mode portion 58 u of the path, i.e., thattunneling isn't always advisable, the user mode portion 58 u of the path58 is also traversed and authenticated in the manner shown in FIG. 15and discussed above in connection with the kernel portion 58 k of thepath 58. To authenticate each module 62 in the user mode portion 58 k ofthe path 58, such user mode module 62 should already have an appropriatecertificate 64 as received from a certifying authority. Of course, ifsuch a certificate 64 is required and not present, such user mode module62 cannot be authenticated. Other authenticating measures aside from acertificate 64 may be employed without departing from the spirit andscope of the present invention.

Notably, traversal of the user mode portion 58 u of the path 58 islikely more difficult than traversal of the kernel portion 58 k of thepath. Reasons for such difficulty include the likelihood that the usermode portion 58 u is larger than the kernel portion 58 k, the likelihoodthat the user mode portion 58 u has more complex data branching, joiningand looping structures than the kernel portion 58 k, and the likelihoodthat at least some of the modules 62 in the user mode portion 58 u donot have authenticating measures such as certificates 64, among otherthings. In an effort to mitigate such difficulty, and recognizing thatsome sub-portions 58 s of the user mode portion 58 k of the path 58should not substantively change the naked digital content 12 or areotherwise non-essential, and yet are relatively long, each suchsub-portion 58 s is identified by the DRM system 32 and tunneled in themanner set forth above and shown in FIG. 14. That is, at a module 62just before such sub-portion 58 s, the digital content 12 is scrambled(step 1401), and at a module 62 just after such sub-portion 58 s, thescrambled digital content 12 is de-scrambled (step 1405). Such tunneledsub-portion(s) 58 s thus need not be authenticated by the DRM system 32.

The scramble/de-scramble functionality may be built into each module 62so that the DRM system 32 can turn on/turn off such functionality asneeded in any sub-portion 58 s of the path 58. Alternatively, dedicatedscramble/de-scramble modules 62 may be built into the path 58 inappropriate locations beforehand without departing from the spirit andscope of the present invention.

In an embodiment of the present invention as described above, if even asingle module 62 in the user portion 58 u or the kernel portion 58 k ofthe path 58 fails to authenticate itself to the satisfaction of the DRMsystem 32, such DRM system 32 declares the path 58 suspect and refusesto release the digital content 12 to the rendering application 34 andbeyond (steps 1511, 1513 of FIG. 15). However, in an alternateembodiment, for each non-authenticated module 62 (in the user modeportion 58 u or the kernel portion 58 k of the path 58), such DRM system32 defines an appropriate sub-portion 58 s including thenon-authenticated module 62 and tunnels such sub-portion 58 s in themanner described above in connection with FIG. 14 (step 1517 of FIG.15). Thus, the DRM system 32 can then declare the altered path 58trustworthy and thereby release the digital content 12 to the renderingapplication 34. Of course, tunneling a sub-portion 58 s having anon-authenticated module 62 may degrade the path 58 somewhat, perhaps toan unacceptable level.

As is known, a certificate 64 provided by a certifying authority can andat times does become compromised in that the ‘secret’ of the compromisedcertificate 64 becomes discovered and/or public knowledge. Oncecompromised, a certificate 64 can be proffered by anyone, including anefarious entity who wishes to do a non-trustworthy act. For example,such a nefarious entity can attach a compromised certificate 64 to anefarious module in the path 58. Thus, the nefarious module 62 canproffer the compromised certificate 64 to the DRM system 32 to gain thetrust of such DRM system 32, and nevertheless thereafter perform anon-trustworthy act such as storing digital content 12 in a naked and/ornon-secure form.

When such a compromised certificate 64 comes to light, the certifyingauthority that issued such certificate 64 or another party hopefully ismade aware of the compromised state thereof. Such certifying authorityor other party therefore regularly issues a list of certificates 64 thatare not to be trusted anymore (i.e., have been ‘revoked’). In oneembodiment of the present invention, a list 66 of revoked certificates64 is regularly provided to the DRM system 32, and such DRM system 32stores such revocation list 66 in a secure location such as the statestore 40 (FIG. 4) to prevent tampering therewith.

Accordingly, and referring now to FIG. 16, as part of authenticatingeach module 62, the DRM system 32 of the present invention reviews theproffered certificate 64 upon receipt from the module 62 and determinesif the received certificate 64 is acceptable for purposes ofauthenticating the module 62 (step 1601); and also checks the revocationlist 66 to ensure that a proffered certificate from a module 62 has notbeen revoked (step 1603). If revoked, the module is treated by the DRMsystem 32 as if non-authenticated. Preferably, the DRM system 32regularly obtains/downloads a current revocation list 66 and/orregularly update a resident revocation list 66. Such objective can befulfilled by for example obtaining/downloading of a current revocationlist 66 prior to obtaining a new black box 30, a new license 16, newdigital content 10, or the like. Alternatively such objective can befulfilled by for example updating of a resident revocation list 66 priorto obtaining a new black box 30, a new license 16, new digital content10, or the like. Such downloading/obtaining/updating may be performed asa requirement or may be performed automatically and/or transparently. Ofcourse, other methods of fulfilling the objective may be employedwithout departing from the spirit and scope of the present invention.

Further Concepts—Security Approval by Way of Specified Security Values

As discussed above, the DRM system 32 and/or the black box 30authenticates the rendering application 34 and the path 58 to ensurethat such items can be trusted to handle the decrypted or ‘naked’digital content 12 in an appropriate manner. In one embodiment of thepresent invention, the performed authentication of the renderingapplication 34 and/or the path 58 includes verifying that the renderingapplication 34 and/or each module 62 in the path 58 is of a type secureenough to be approved for use by the digital license 16.

Many different options are available for specifying types of securityfor a rendering application 34 or module 62 that is approved for use bya digital license 16. For example, the digital license 16 mayappropriately specify that the rendering application 34 or module 62must be from one or more particular sources/suppliers/developers, mustbe one or more particular products, must be one or more particularversions of a particular product, or the like. However, it is to beappreciated that such specifications are overly limiting in that theymay unnecessarily exclude other (perhaps newer)sources/suppliers/developers, other (perhaps newer) particular products,other (perhaps newer) particular versions of a particular product, orthe like.

In one embodiment of the present invention, then, a type of security ofa rendering application 34 or module 62 that is to be approved for useby a digital license 16 is specified in such digital license 16 in aflexible and robust manner that is not overly limiting. In particular,such security type is specified in a scaled manner. One preferredsecurity scale is a numerical scale, whereby each rendering application34 or module 62 is assigned a number representative of the relativesecurity thereof, and the digital license specifies a range within whichthe number must be if the rendering application 34 or module 62 is to beapproved for use. However, other security scales may be employed withoutdeparting from the spirit and scope of the present invention. Such otherscales may for example include letter scales (A, A−, B+, B, etc.; AAA,AA, A, BBB, BB, etc.; e.g.), plus/minus scales (+++, ++, +, −, −−, etc.,e.g.) or the like.

With regard to a numerical security scale, in one embodiment of thepresent invention, each rendering application 34 or module 62 beassigned a security value based on a number scale from 0 to 100, where 0is indicative of a rendering application 34 or module 62 that has beendeemed not secure, and where 100 is indicative of a renderingapplication 34 or module 62 that has been deemed highly secure.Correspondingly, a digital license 16 may require that each renderingapplication 34 or module 62 have a pre-assigned security value of atleast 50, greater than 40, 20 or higher, or the like. Such a securityrequirement 68 is shown in FIG. 8. Such digital license 16 may of coursespecify other ranges, and may also specify different types of ranges(between 20 and 70, no greater than 60, etc.), all without departingfrom the spirit and scope of the present invention.

In one embodiment of the present invention, the security value 70 ofeach rendering application 34 or module 62 is specified in the form of acertificate 72 attached to the rendering application 34 (as shown inFIG. 4) or module 62. Such certificate 72 is issued by a security valuecertifying authority that determines the security value 70 based onpre-determined parameters. Preferably, the certificate 72 is encryptedto prevent tampering therewith, and is tied to the rendering application34 or module 62 in such a manner that the certificate 72 is inoperablewith any other rendering application 34 or module 62. For example, thecertificate 72 may include a hash based on the rendering application 34or module 62, and the hash is verified when the certificate 72 isexamined.

The security value certifying authority issuing the certificate 72having the security value 70 may be any appropriate certifyingauthority. However, it is to be recognized that anyone can act as acertifying authority and issue a certificate. Thus, a nefarious entitycould issue an improper certificate 72 on its own behalf, or a laxcertifying authority could issue an improper certificate 72 to anefarious entity. Accordingly, the security value certifying authorityis preferably one trusted by the digital license 16. Such trust may forexample be established by explicitly stating indicia of one or more suchtrusted security value certifying authorities 74 in the digital license16 (FIG. 8), whereby a certificate 72 from a non-named security valuecertifying authority is not trusted. Such trust may alternately beestablished, for example, by stating indicia of such trusted securityvalue certifying authorities in the black box 30 and/or the DRM system32.

The method employed by the trusted security value certifying authority74 to determine the security value 70 as specified in the certificate 72may be any appropriate method without departing from the spirit andscope of the present invention. Such method may be objective,subjective, or a combination thereof, also without departing from thespirit and scope of the present invention. Factors going into aconsideration of the security value 70 may include, for example, theparticular source/supplier/developer of the rendering application 34 ormodule 62 at issue, the tamper-resistance of the rendering application34 or module 62 at issue, whether any associated keys in the renderingapplication 34 or module 62 at issue are well-hidden, what kind ofhistory of trust has been established with regard to the renderingapplication 34 or module 62 at issue, and the like, among other things.

In fact, in one embodiment of the present invention, based on suchfactors and others, the security value 70 as specified in thecertificate 70 may instead or in addition comprise a plurality ofsecurity sub-values 70 a, 70 b, etc. (FIG. 4) As should be understood,each sub-value 70 a, 70 b, could be indicative of one factor, or afunction of one or more factors. Correspondingly, the securityrequirement 74 of the digital license could specify required ranges foreach sub-value 70 a, 70 b, etc., could specify required ranges for theresult of functions of the sub-values 70 a, 70 b, etc., or the like.

In one embodiment of the present invention, and referring now to FIG.17, the DRM system 32 and/or the license evaluator 36 (hereinafter ‘theDRM system 32’) approves a rendering application 34 or module 62 for usein accordance with the terms of a digital license 16 in the followingmanner. Preliminarily, the DRM system 32 examines the terms of thedigital license 16 and extracts from such digital license 16 thesecurity requirement 68 and any trusted security value certifyingauthority information 74, as was discussed above (step 1701). The DRMsystem 32 also obtains from the rendering application 34 or module 62the attached certificate 72 having the security value information 70, 70a, 70 b, etc. and indicia of the security value certifying authority 76(FIG. 4) therein (step 1703). The DRM system 32 then examines thecertificate 72 in an appropriate manner to verify that such certificate72 is indeed for such rendering application 34 or module 62 (step 1705),and obtains from the certificate 72 the security value information 70,70 a, 70 b, etc. therein and the indicia of the security valuecertifying authority 76 that issued such certificate 72 (step 1707).

With the security requirement 68 from the digital license 16 and thesecurity value information 70, 70 a, 70 b, etc. from the renderingapplication 34 or module 62, the DRM system 32 compares the securityvalue 70, 70 a, 70 b, etc. to the security requirement 68 toappropriately determine whether such the security value 70, 70 a, 70 b,etc satisfies such security requirement 68 of the digital license 16(step 1709). Of course, such determination may involve an appropriateconsideration of any ranges specified in the security requirement 68,appropriate calculations based on any functions specified by thesecurity requirement 68, or the like. With the trusted security valuecertifying authority information 74 from the digital license 16 and theindicia of the security value certifying authority 76 from the renderingapplication 34 or module 62, the DRM system 32 compares the indicia ofthe security value certifying authority 76 to the trusted security valuecertifying authority information 74 to appropriately determine whethersuch security value certifying authority 76 satisfies such trustedsecurity value certifying authority information 74 from the digitallicense 16 (step 1711).

Assuming that the security value 70, 70 a, 70 b, etc. does satisfy thesecurity requirement 68 (a security value of 58 and a requirement ofgreater than 50, for example) and that the security value certifyingauthority 76 does satisfy the trusted security value certifyingauthority information 74, the DRM system 32 approves the renderingapplication 34 or module 62 and thus verifies that the renderingapplication 34 or module 62 meets the security criteria as set forth bythe digital license 16 (steps 1713, 1715. Of course, if the securityvalue 70, 70 a, 70 b, etc. does not satisfy the security requirement 68(a security value of 58 and a requirement of greater than 60, forexample) or if the security value certifying authority 76 does notsatisfy the trusted security value certifying authority information 74,the DRM system 32 does not approve such rendering application 34 ormodule 62, and rendering of the corresponding digital content 10 is notpermitted (step 1713, 1717).

The aforementioned process for approving a rendering application 34 ormodule 62 as is shown in FIG. 17 may be performed at any appropriatetime without departing from the spirit and scope of the presentinvention. For example, the approval process may be performed duringlicense evaluation as discussed above and shown in FIG. 6, or may beperformed as part of path authentication as discussed above and shown inFIG. 15. Moreover, the approval process for the rendering application 34may for example take place at a time different than for a module 62, ifin fact any module is in fact to be approved in the manner shown in FIG.17.

Further Concepts—Deriving the Content Key from the Key ID

As was discussed above, in one embodiment of the present invention, thedecryption key (KD) and key ID (among other things) for each piece ofdigital content 12 (or each package 12 p) is stored in the content-keydatabase 20 (FIG. 1). Thus, based on information associated with areceived license request, a license server 24 can interrogate thecontent-key database 20 and locate a record corresponding to the digitalcontent 12 (or package 12 p) that is the basis of the request.

However, it is to be appreciated that such content-key database 20 willlikely become a mammoth size once such database 20 is loaded withinformation for each of a multitude of pieces of digital content 12.Such mammoth size of course increases the likelihood that thecontent-key database 20 will become corrupted, and accordingly aconsiderable amount of staff and/or resources must be dedicated tomaintaining such database 20 and keeping such database 20 up andrunning. Moreover, such mammoth size likely will require that thedatabase 20 reside on its own server (not shown), and will require highspeed communications resources to communicate with one or more authoringtools 18, one or more content servers 22, one or more license servers24, and the like in an efficient manner, especially if any such elementsare remote from the database 20. Further, and as should be appreciatedby now, the amount of communications between the one or more authoringtools 18, one or more content servers 22, one or more license servers24, and the like will be considerable.

In one embodiment of the present invention, then, such content-keydatabase 20 is avoided by deriving the content decryption key (KD) for apiece of digital content 12 directly from the key ID associated withsuch digital content 12. In particular, in such embodiment, a licenseserver issuing a license 16 to a user's computing device 14 obtains thedecryption key (KD) to be included with such license 16 from the key IDincluded with the license request for such license 16.

In such embodiment, then, and referring now to FIG. 18, the authoringtool 18 authoring such digital content 12 or the content server 22serving such digital content 12 selects a key ID for the digital content12 (step 1801), and the content server 22 then employs the selected keyID as an input to a function f( ), perhaps along with a secret ‘seed’(step 1803). The output of such function f( ) is then employed as thesymmetric encryption and decryption key (KD) for the digital content 12:

-   -   f(key ID, seed)        key (KD),        (step 1805) and such digital content 12 is therefore encrypted        according to such key (KD) (step 1807). Such encrypted digital        content 12 may thereafter be distributed to a user's computing        device 14 (step 1809).

The selection of the key ID for the digital content 12 (step 1801) maybe performed in any reasonable manner without departing from the spiritand scope of the present invention. For example, such selection may bedone randomly, serially, or the like. Moreover, the key ID may be anyparticular length, have any particular base, be alphanumeric, or haveother features, again without departing from the spirit and scope of thepresent invention.

Importantly, the function f( ) is a one-way function. As may beappreciated, in a one-way function, deriving the output from theinput(s) and the secret seed is relatively easy, but deriving the seedfrom the input(s) and the output is extremely difficult. Accordingly, anefarious entity with knowledge of the particular one-way function, akey ID inputted to the function, and the key (KD) derived from thefunction and the key ID cannot derive the secret seed without enormouseffort. Of course, if such nefarious entity should be able to discoverthe seed, it can access any encrypted digital content 12 encryptedaccording to a key (KD) derived from the seed merely by knowing the keyID for such digital content 12.

Any particular one-way function may be employed without departing fromthe spirit and scope of the present invention. For example, a one-wayhash function such as a secure hashing algorithm (SHA) or MD5 may beemployed. The MD5 algorithm is marketed and/or distributed by RSASecurity of Bedford, Mass. and/or a related entity. The details ofone-way functions are known or are apparent to the relevant public andtherefore need not be described herein in any further detail.

As was discussed above, one or more license servers 24 are authorized toissue a digital license 16 for the distributed digital content 12.Preferably, such authorized license servers 24 are provided with thefunction f( ) and the seed used to produce the key (KD) that wasemployed to encrypt such distributed digital content 12 (step 1811).Accordingly, when a digital license 16 is requested from one of suchlicense servers 24 (step 1813), and assuming the request has beenapproved, the license server 24 can obtain the decryption key (KD) toinclude with the requested digital license 16.

For the license server 24 to obtain such decryption key (KD) inaccordance with the embodiment presently discussed, such license server24 must of course be supplied with the corresponding key ID (step 1815).Preferably, such key ID is supplied as part of the license requestinformation provided in the course of a request for a digital license 16(step 703 of FIG. 7). As may be recalled, and with reference to FIG. 3,such key ID is included with the digital content package 12 p thatcontains the encrypted digital content 12 (step 1808), and is thusobtainable therefrom by the user's computing device 14. Once the licenseserver 24 has approved the license request, such license server 16obtains the key ID for the digital content 12 from the license requestinformation (step 1817), and then employs the obtained key ID as aninput to the function f( ) along with the secret seed employed by thecontent server 22 (step 1819). Preferably, the license server 24 andcontent server 22 agree on the secret seed beforehand. Based on such keyID and such seed, such function f( ) should of course output theappropriate decryption key (KD) for the digital content 12:

-   -   f(key ID, seed)        key (KD)        (step 1821). The license server 24 therefore appropriately        packages such key (KD) in the digital license 16 that is to be        sent out in response to the license request (step 1823). Such        digital license 16 with such key (KD) may thereafter be so sent        out to the requester's computing device 14 (step 1825).

As may now be appreciated, in the embodiment of the present inventioncurrently being discussed, the license server 24 can issue a digitallicense 16 for digital content 12 issued by the content server 22because the license server 24 and the content server 22 share knowledgeof the function f( ) and secret seed employed to produce a symmetricencryption/decryption key (KD) based on a selected key ID. Assuming thatthe function f( ) is known, then, if a nefarious entity somehow shoulddiscover the seed, such nefarious entity can access any encrypteddigital content 12 encrypted according to a key (KD) derived from theseed merely by knowing the key ID for such digital content 12.

Unfortunately, it must be expected that such a nefarious entity willindeed discover the secret seed. Accordingly, in one embodiment of thepresent invention, the seed is changed frequently. The period of suchchange can of be any period without departing from the spirit and scopeof the present invention. For example, such period may be weekly, daily,monthly, etc. In addition, such period may be irregular, again withoutdeparting from the spirit and scope of the present invention.

An additional reason for employing multiple seeds is to establishisolated pairings between content servers 22 and license server 24.Thus, a license server 24 would not be able to issue a license 16 fordigital content 12 unless the issuing content server 22 thereof agreedbeforehand on a seed with such license server 24.

Of course, if the seed changes regularly, and/or if multiple seeds areemployed, a license server 24 issuing a digital license 16 for digitalcontent 12 issued by a content server 22 must know which seed wasemployed to encrypt such digital content 12. Accordingly, in oneembodiment of the present invention, the seed is identified by a seedID, and such seed ID is included along with the key ID in the digitalcontent package 12 p that contains the encrypted digital content 12(FIG. 3). Preferably, such seed ID is supplied along with the key ID aspart of the license request information provided in the course of arequest for a digital license 16 (step 703 of FIG. 7). Thus, once thelicense server 24 has approved the license request, such license server16 obtains the key ID and seed ID for the digital content 12 from thelicense request information (step 1817), and then employs the obtainedkey ID as an input to the function f( ) along with the appropriate seedas previously provided to such license server 24 (step 1819). Of course,here, the appropriate seed is selected based on the obtained seed ID.Based on such key ID and such seed, such function f( ) should of courseoutput the appropriate decryption key (KD) for the digital content 12,as was discussed above (step 1821).

In another embodiment of the present invention, the seed ID is employedas an input to the function f( ). In particular, in such embodiment, theauthoring tool 18 authoring such digital content 12 or the contentserver 22 serving such digital content 12 selects a key ID for thedigital content 12 (step 1801), and then employs the selected key ID asan input to a function f( ) along with a secret ‘seed’ and the seed IDfor such seed (step 1803). The output of such function f( ) is thenemployed as the symmetric encryption and decryption key (KD) for thedigital content 12:

-   -   f(key ID, seed, seed ID)        key (KD),        (step 1805) and such digital content 12 is therefore encrypted        according to such key (KD) (step 1807). Such encrypted digital        content 12 may thereafter be distributed to a user's computing        device 14 (step 1809).

As was discussed above, one or more license servers 24 are authorized toissue a digital license 16 for the distributed digital content 12.Preferably, such authorized license servers 24 are provided with thefunction f( ), each applicable seed used to produce a key (KD), and theseed ID for each applicable seed (step 1811). Also preferably, eachlicense server 24 includes an appropriate seed database 24 s (FIG. 1)for storing such seed and seed ID information. Accordingly, when adigital license 16 is requested from one of such license servers 24(step 1813), and assuming the request has been approved, the licenseserver 24 can obtain the decryption key (KD) to include with therequested digital license 16.

For the license server 24 to obtain such decryption key (KD), suchlicense server 24 must of course be supplied with the corresponding keyID and seed ID (step 1815). Preferably, and as was discussed above, suchkey ID and seed ID are supplied as part of the license requestinformation provided in the course of a request for a digital license 16(step 703 of FIG. 7). As may again be recalled, and with reference toFIG. 3, such key ID and seed ID are included with the digital contentpackage 12 p that contains the encrypted digital content 12 (step 1808),and is thus obtainable therefrom by the user's computing device 14. Oncethe license server 24 has approved the license request, such licenseserver 16 obtains the key ID and seed ID for the digital content 12 fromthe license request information (step 1817), and then employs theobtained key ID and seed ID as inputs to the function f( ) along withthe appropriate seed as previously provided to such license server 24and as selected based on the seed ID from the seed database 24 s (steps1818, 1819). Based on such key ID, such seed, and such seed ID, suchfunction f( ) should of course output the appropriate decryption key(KD) for the digital content 12:

-   -   f(key ID, seed, seed ID)        key (KD)        (step 1821). The license server 24 therefore appropriately        packages such key (KD) in the digital license 16 that is to be        sent out in response to the license request (step 1823). Such        digital license 16 with such key (KD) may thereafter be so sent        out to the requester's computing device 14 (step 1825).

By using multiple seeds and a seed ID for each seed, then, even if anefarious entity somehow should discover one seed, such nefarious entitycan only access encrypted digital content 12 encrypted according to akey (KD) derived from such seed. Correspondingly, such nefarious entitycannot access any encrypted digital content 12 encrypted according to akey (KD) derived from any other seed.

Further Concepts—Individualization of Black Box 30

As was discussed above, particularly with reference to FIG. 9, the DRMsystem 32 obtains a new and unique (‘individualized’) black box 30 froma black box server 26 or the like (FIG. 1), and such black box server 26delivers the individualized black box 30 with a new public/private keypair (PU-BB, PR-BB) (and/or with other secrets and/or individualizingelements). In one embodiment of the present invention, the black boxserver 26 individualizes each black box 30 by individualizing anexecutable program file that is delivered to and is resident on the DRMsystem 32/the user's computing device 14. Such executable program filemay be a .dll (dynamically linked library) file, such as ‘bb.dll’,although other types of files may be employed without departing from thespirit and scope of the present invention.

Preferably, the individualization of the bb.dll or the like is performedin a manner such that the bb.dll and DRM system 32 are BORE (Break OnceRun Everywhere) resistant in that a successful attack by a nefariousentity on one bb.dll/DRM system 32 cannot easily be replicated on anyother bb.dll/DRM system 32. As may be appreciated, the bb.dll executableis individualized since such executable contains the ‘secret’ that isthe goal of such attack.

One method for implementing BORE-resistance is disclosed in detail inU.S. patent application Ser. No. ______, entitled “BORE-ResistantDigital Goods Configuration and Distribution Methods And Arrangements”and filed Mar. 14, 2000 (Attorney Docket No. MS1-394US/131064.1), herebyincorporated by reference. Briefly, the method of BORE-resistancedisclosed in such document is achieved in a manner akin to codeoptimization. As is known, code optimization is a process performed by asoftware and/or hardware tool such as a code optimizer or the like (notshown). The code optimizer receives a piece of executable code andoptimizes such code based on predetermined optimization parameters. Inessence, the code optimizer re-arranges portions of the code accordingto the optimization parameters to produce an optimized version that isfunctionally equivalent (i.e., performs the same functions) butoperationally optimized. A plurality of identical copies of theoptimized code may then be widely distributed.

However, if the aforementioned code optimizer is run a plurality oftimes, each time based on randomized parameters, a correspondingplurality of versions of randomized code are produced, where eachrandomized version of code is functionally equivalent but operationallydifferent. In effect, the code optimizer in such a situation is operatedas a code randomizer 78 in connection with the black box server 26, asis seen in FIG. 19. Importantly, each operationally different version ofcode operates with a different program flow, among other things.Accordingly, a determination of the program flow of one version to findthe secret in the one version is inapplicable to a determination of theprogram flow of another version to find the secret in the anotherversion. Therefore, the ‘breaking’ of one version is not the breaking ofany other version. Put simply, a piece of code randomized by such a coderandomizer 78 is BORE-resistant. Accordingly, in one embodiment of thepresent invention, an individualized bb.dll 80 is produced by inputtinga master bb.dll 80 m and random parameters 81 to a code optimizeroperating as the aforementioned code randomizer 78. Of course, othercode randomizing agents may be employed without departing from thespirit and scope of the present invention.

In one embodiment of the present invention, and referring now to FIGS.20A-20C, a new individualized bb.dll 80 is requested from a black boxserver 26 or the like by a DRM system 32 each time a triggering event(‘trigger’) requires such new bb.dll (steps 2001, 2003 of FIG. 20A, step901 of FIG. 9). As was discussed above, the triggering event may be adetermination that the black box 30/individualized bb.dll 80 is notcurrent, or may be some other event without departing from the spiritand scope of the present invention. Such determination may be made bythe license server 24, as was discussed above, or by another device,again without departing from the spirit and scope of the presentinvention. In response, to the request, the black box server 26 preparessuch a new individualized bb.dll 80 and forwards same to the requestingDRM system 32.

As was discussed above, the black box server 26 delivers the newindividualized bb.dll 80 with a new public/private key pair (PU-BB,PR-BB), and perhaps other keys, as will be discussed below(collectively, a ‘new key set’). Importantly, the new individualizedbb.dll 80 should still be able to employ old key sets previouslydelivered to the DRM system 32 on the user's computing device 14 inconnection with old bb.dlls 80. As may be appreciated, such old key setsare still necessary to access older digital content 12 and oldercorresponding licenses 16 that were generated according to such old keysets. Accordingly, such new individualized bb.dll 80 is provided withaccess to old key sets and old public/private key pairs. In particular,in one embodiment of the present invention, the black box server 26includes a key manager 84 (FIG. 19) that prepares a corresponding newkey file 82 along with the new individualized bb.dll 80, where the newkey file 82 includes the old key sets and perhaps the new key set(PU-BB, PR-BB, etc.). Such key manager 84 of such black box server 26then forwards the corresponding new key file 82 to the requesting DRMsystem 32 along with the new individualized bb.dll 80.

Note that if the new key set (PU-BB, PR-BB, etc.) is not included in thenew key file 82, such new key set may instead be included with the newindividualized bb.dll 80, preferably with at least (PR-BB) hidden. Inany case, the key file 82 is encrypted and the bb.dll 80 includes a‘secret’ that allows it to gain access to the encrypted key file 82. Thesecret may be the new black box private key (PR-BB) in which case thekey file 82 is encrypted according to the new black box public key(PU-BB). Alternatively, the secret may be another key, such as asymmetric key, in which case the key file 82 is encrypted according tosuch symmetric key. Other types of secrets may of course be employed,and only the old key sets in the key file 82 may be encrypted, allwithout departing from the spirit and scope of the present invention.

Referring still to FIGS. 19 and 20, the process of preparing the newindividualized bb.dll 80 (i.e., the ‘(n)th bb.dll 80’) and the new keyfile 82 (i.e., the ‘(n)th key file 82’) by the key manager 84 inresponse to a request from a DRM system 32 may take place in thefollowing manner. Such process may be initiated by a request from theDRM system (step 2003), or by a user request, for example. As will beexplained in more detail below, such request may be accompanied by oneor more pieces of information, chief among which is the old key file 82(i.e., the ‘(n−1)th key file 82’) (step 2005). Preferably, the (n−1)thkey file 82 is sent to the black box server 26 along with a digitalsignature verifying such (n−1)th key file 82. Alternatively, the digitalsignature could verify the entire request including such (n−1)th keyfile 82 and all other contents.

In response to the request, the key manager 84 checks the digitalsignature to verify same and proceeds if the verification is positive(step 2007). The key manager 84 then obtains the (n−1)th key file 82from the request and the old/old and new key sets therein (step 2011).However, the (n−1)th key file 82 and/or the key sets therein areencrypted according to the secret of the old bb.dll 80 (i.e., the‘(n−1)th bb.dll 80’), as was discussed above. Accordingly, to obtain thekey sets in the (n−1)th key file 82, the DRM system 32 must include thesecret of the (n−1)th bb.dll 80 with the request for the (n)th bb.dll80. Of course, this runs counter to the notion that the secret shouldnever be revealed to the world outside the bb.dll 80, especially if thesecret is PR-BB. Nevertheless, such secret must somehow be supplied tothe black box server 26 and key manager 84.

If the secret is embedded in the bb.dll 80, such secret may be suppliedto the key manager 84 by including a copy of the entire bb.dll 80 in therequest. However, doing so may be cumbersome, especially if such bb.dll80 is relatively large. Alternatively, the key manager 84 may employ anappropriate database to remember the secret from when the bb.dll 80 wasoriginally issued. However, such database could become exceedingly largeand therefore unwieldy.

In one embodiment of the present invention, then, the secret ispreferably already present in the key file 82 that has already beendelivered such that the key manager 84 can obtain the secret from suchkey file 82 (step 2009). The key manager 84 can then employ the obtainedsecret to in turn obtain the (n−1)th key file 82 from the request andthe old key sets therein (step 2011). Specifically, in such embodiment,when the key manager 84 prepared the (n−1)th bb.dll 80 (with an (n−1)thsecret) and the (n-1)th key file 82, such key manager 84 included insuch (n−1)th file 82 the (n-1)th secret, whether it be (PR-BB) or someother secret. Thus, when the key manager 84 needs the (n−1)th secret inorder to access the (n−1)th key file 82 for purposes of preparing the(n)th key file 82, such (n−1)th secret is already available in such(n−1)th key file 82. Of course, such (n−1)th secret must be in the(n−1)th key file 82 in a form available to the key manager 84, but notavailable to the remainder of the world.

As an alternative, the secret is already present at the black box server26/key manager 84, in that an appropriate database including such secretis maintained by such black box server 26/key manager 84. However, thisis not especially advisable, based on security reasons, the size andcomplexity of such a database, and difficulties in sharing such databasewith multiple black box servers 26/key managers 84 if need be.

Preferably, then, the (n−1)th secret is encrypted according to a ‘SUPER’key known only to the black box server 26/key manager 84(SUPER(secret)), as is seen in FIG. 19. Parenthetically, then, it is tobe noted that the key sets in such (n−1)th key file 82 are encryptedaccording to the (n−1)th secret (secret(key sets)), and the attacheddigital certificate is based on both (SUPER(secret)) and (secret(keysets)). Of course, alternate key file arrangements may be employedwithout departing from the spirit and scope of the present invention.For example, if the (n−1)th secret is embodied in the (n−1)th key set,the (n−1)th key file 82 may include (SUPER(key sets)), (secret(keysets)), and an appropriate attached digital certificate.

Note, though, that in some instances, an entity other than the black boxserver 26/key manager 84 may build the key file 82, in which case suchother entity would not have access to the ‘SUPER’ key. Such an instancemay for example occur on an initial build of a DRM system 32 on acomputing device 14, where the DRM system 32 in essence builds aninitial key file 82 itself. In such case, such other entity is providedwith and uses a black box server public key (PU-BBS) instead of the‘SUPER’ key to encrypt (key sets). Here, of course, only the black boxserver 26/key manager 84 has the corresponding black box server privatekey (PR-BBS) which it may use instead of the ‘SUPER’ key to decrypt (keysets).

Thus, based on the old key sets from the (n−1)th key file 82, the keymanager 84 can place all appropriate key sets in the (n)th key file 82(step 2017). Note that in doing so, the key manager 84 either selects oris provided with the new key set including the black box key pair(PU-BB, PR-BB, etc.) (step 2013), and uses the secret incumbent in suchnew key set to encrypt the key sets to be placed in such (n)th key file82 (step 2015). As will be discussed below, such secret is then notedfor later use (step 2019)in provided therein. As may be appreciated, anyparticular methods and structures may be employed to place such key setsin such (n)th key file 81 without departing from the spirit and scope ofthe present invention as long as such (n)th key file 82 is provided withall necessary key sets in a form readable by the (n)th bb.dll 80.

Moreover, to tie the (n)th key file 82 and by extension the (n)th bb.dll80 to the user's computing device 14, the key manager 84 preferablyobtains a hardware ID (HWID) from the (n−1)th key file 82 or from theinitial black box request (step 2021), and then appropriately placessuch HWID in the (n)th key file 82 (as shown in FIG. 19), or in anotherfile to be delivered to the user's computing device 14 (step 2023). Asmay be appreciated, the HWID is originally obtained from such computingdevice 14, and in fact may be any appropriate identification that can beobtained from an appropriate memory location on the user's computingdevice 14 and that in fact identifies such computing device 14. Forexample, the HWID may be a CPU ID on the computing device 14, anidentifier hidden in a non-volatile memory on the computing device 14,an identifier developed from indicia of elements of the computing device(size of hard drive, size of RAM, etc.), or the like. The HWID may beplaced in the (n)th key file 82 in an encrypted form, or may be leftunencrypted if verifiable by way of a digital signature or the like.

Of course, the (n)th bb.dll 80 must still be prepared. To do so, thecode randomizer 78 of the black box server 26 is run with randomizedparameters 81 and the master bb.dll 80 m as the inputs to produce anindividualized bb.dll 80 with space reserved for additional information(step 2025, FIG. 20B). Such randomized parameters 81 may be selected inany appropriate manner without departing from the spirit and scope ofthe present invention. For example, such randomized parameters 81 may betruly random, or may include information as received in connection withthe request, such as the HWID (step 2003). If the HWID is employed as arandomized parameter 81, such HWID may be obtained in connection withstep 2021.

Preferably, the code optimizer 78 notes where the reserved spaces arelocated in the produced individualized bb.dll 80 (step 2027), andprovides such information and such produced individualized bb.dll 80 toan injector 86 (step 2029), as seen in FIG. 19. As may be appreciated,the reserved spaces in the produced bb.dll 80 are for receiving thesecret as saved by the key manager 84 (step 2019), and the injector 86receives the information on the reserved spaces and the producedindividualized bb.dll 80, retrieves the saved secret (step 2031), andthereafter ‘injects’ such secret into such received bb.dll 80 in thereserved spaces (step 2033). As may be appreciated, the reservedspace(s) in the bb.dll 80 may comprise any appropriate structure(s) atany appropriate location(s) without departing from the spirit and scopeof the present invention, as long as the reserved space(s) are adequatefor the purpose of holding the secret. Moreover, since the secret is infact a secret, the secret is injected into the reserved spaces in such amanner and the reserved spaces are arranged in such a manner to hide thesecret to a sufficient degree such that the secret cannot be found inany practical manner by a nefarious entity. Any appropriate manner ofinjection may be employed without departing from the spirit and scope ofthe present invention.

Preferably, the reserved spaces are varied with respect to eachindividualized bb.dll 80 as part of the individualization processperformed by the code randomizer 78. Also preferably, the code for theindividualized bb.dll 80 is written and/or the code randomizer 78 isoperated such that the bb.dll 80 can locate the secret within itselfduring operation thereof. The injector 86 may encrypt the secret in somefashion as part of the injection process, perhaps according to the HWIDof the requesting computing device 14, but appropriate decryptioninformation must be provided to the bb.dll 80 by such injector 86 oranother element to allow the bb.dll 80 to decrypt such encrypted secret.The injector 86 may also inject the HWID into the received bb.dll 80 ina portion of the reserved spaces (step 2033). If the HWID is employed inconnection with the injector 86 and/or step 2033, such HWID may beobtained in connection with step 2021.

In one embodiment of the present invention, the information provided bythe code randomizer 78 to the injector 86 includes a help file or thelike appropriately specifying how the secret is to be injected into thebb.dll 80. In another embodiment, such a help file or the like isembedded in the bb.dll 80 in a manner readable by the injector 86.

Notably, the injector 86 may inject other information intoalready-reserved spaces in the bb.dll 80 without departing from thespirit and scope of the present invention. For example, to tie suchbb.dll 80 more closely to the user's computing device, the injector 86may appropriately inject the HWID received as part of the request (step2003). Likewise, if there are multiple black box servers 26, theinjector 86 may appropriately inject an identifier of the black boxserver 26 issuing such bb.dll 80 to tie such bb.dll 80 to such black boxserver 26.

Once the injector 86 has injected the secret and any other informationinto the (n)th bb.dll 80, such (n)th bb.dll 80 and the corresponding(n)th key file 82 are essentially ready for delivery to the requestingcomputing device 14. However, prior to delivery, such (n)th bb.dll 80 ispreferably delivered to a signature generator 88 (FIG. 19) thatgenerates a digital signature for the bb.dll and that couples thegenerated digital signature to the (n)th bb.dll 80 in an appropriatemanner (step 2035). As may be appreciated, such digital signature isemployed (for example) to assist the computing device 14 in checkingsuch (n)th bb.dll 80 for the presence of computer viruses, but may alsobe employed by the DRM system 32 of the requesting computing device 14as a tool to otherwise verify that such (n)th bb.dll 80 has not beenaltered.

Prior to delivering the (n)th bb.dll 80 and the (n)th key file 82 to therequesting DRM system 32, the black box server 26 preferably prepares adigital certificate for the (n)th black box 30 (which is instantiatedbased on the (n)th bb.dll 80) (step 2037). As is to be appreciated, suchdigital certificate may be based on the contents of the (n)th key file82 and/or the (n)th bb.dll 80 and is to be proffered by the black box 30and/or the DRM system 32 upon request to certify to an inquiring entitythat the black box 30 is to be trusted. Such prepared digitalcertificate may then be added to the (n)th key file 82 (as shown in FIG.19) (step 2039), may be added to the (n)th bb.dll 80, or may be placedin another file. It is to be noted that if the digital certificate isbased at least in part on the HWID, such HWID need not be encrypted inthe (n)th key file 82 since an alteration thereof will cause the digitalcertificate to fail to verify.

Such (n)th bb.dll 80, (n)th key file 82, and any other appropriate filesmay then be delivered to the requesting DRM system 32 (step 2043). Ifnecessary and/or appropriate, a compressor 90 (FIG. 19) may be employedto compress the (n)th bb.dll 80 and/or the (n)th key file 82 prior tosuch delivery (step 2041). If so, the DRM system 32 must include anappropriate de-compressor (not shown) to de-compress the compressed dataupon receipt (step 2045). Such DRM system may then appropriately installand use such (n)th bb.dll 80, (n)th key file 82, and any otherappropriate received files (step 2047).

As should be apparent, the process as outlined in FIGS. 20A-20C isfairly involved, and therefore may require a relatively long time to beperformed. That is, the period of time between the trigger and request(steps 2001, 2003 of FIG. 20A, step 901 of FIG. 9) and the receipt andinstallation of the new black box 30 (steps 2045, 2047 of FIG. 20C,steps 907, 909 of FIG. 9) can be considerable. Accordingly, it may beadvisable to perform some of the steps in FIGS. 20A-20C beforehand.

In one embodiment of the present invention, then, the code randomizer 78is operated beforehand to produce multiple randomized bb.dll's 80, andsuch multiple randomized bb.dll's 80 are stored or ‘placed on the shelf”until needed in response to a request (step 2003). Of course, if suchcode optimizer 78 produces a help file for each bb.dll 80 as wasdiscussed above, such help file should be stored or placed on the shelfwith such bb.dll or stored in some other location. In response to arequest (step 2003), then, one of the bb.dll's 80 is ‘taken from theshelf’ and employed as the (n)th bb.dll 80 to be delivered to therequesting user's computing device 14. Of course, such (n)th bb.dll 80must be injected with the appropriate secret (step 2033), and all otherappropriate steps as shown in FIGS. 20A-20C and discussed above must beperformed. To perform the injection function (step 2033), the help filecorresponding to the taken bb.dll 80 (if such a help file is indeedemployed) must be located and appropriately employed. Since producingeach randomized bb.dll 80 may be a time-intensive task, such coderandomizer 78 may be operated on its own server if need be. Of course,if the code randomizer 78 is operated beforehand, such code randomizercannot be operated based on any information that could be received aspart of the request, such as the HWID. Nevertheless, none of suchinformation is believed to be vital to the code randomization operationperformed by the code randomizer 78.

In a variation on the aforementioned embodiment, the process linecomprising steps 2025-2035 is performed beforehand to produce multiplecompleted randomized bb.dll's 80 with respective secrets alreadyinjected. However, in such variation, each secret is selected andemployed by the injector 86 or the like and is then saved (a la step2019) for later retrieval and use by the key manager 84 or the like (ala step 2031, but at or about step 2013). As before, such completedbb.dll's 80 are stored or ‘placed on the shelf’ until needed in responseto a request (step 2003). In response to such request (step 2003), then,one of the bb.dll's 80 is ‘taken from the shelf’ and employed as the(n)th bb.dll 80 to be delivered to the requesting user's computingdevice 14. Here, the secret already pre-injected into such (n)th bb.dll80 (step 2033) is appropriately retrieved by the key manager 84, and isthen employed to produce the (n)th key file 82 in the manner discussedabove. Here, too, if the process line comprising steps 2025-2035 isperformed beforehand, the (n)th bb.dll 80 cannot be produced based onany information that could be received as part of the request, such asthe HWID. Again, though, none of such information is believed to bevital to the aforementioned process line.

In particular, the bb.dll 80 need not absolutely have the HWID injectedthereinto to tie such bb.dll 80 to the user's computing device 14. Asmay be appreciated, such bb.dll 80 is already tied to such computingdevice 14 because the (n)th key file 82 contains such HWID and istherefore tied to such computing device 14, and only the (n)th bb.dll 80contains the secret that is used to access such (n)th key file 82. Thus,the upgraded black box 30 which includes such (n)th key file 82 and such(n)th bb.dll 80 is tightly tied to or associated with the user'scomputing device 14. Accordingly, such upgraded black box 30 cannot beoperably transferred among multiple computing devices 14 for nefariouspurposes or otherwise, except in the manner to be specified below. Inparticular, such upgraded black box 30 can only be employed on therequesting user's computing device 14. Preferably, if the upgraded blackbox 30 is somehow transferred to another computing device 14, thetransferred black box 30 recognizes that it is not intended for suchother computing device 14, and does not allow any requested rendering toproceed on such other computing device 14.

As was stated beforehand, each bb.dll 80 should be unique with a uniqueset of keys. However, in an alternate embodiment of the presentinvention, such bb.dll 80 is not in fact unique, but instead has afinite number of identical copies. Such number of copies should berelatively small, on the order of 2-100, for example, such that thelikelihood that any two users share an identical bb.dll 80 isnegligible. As may be appreciated, by using the same bb.dll 80 multipletimes (with adding the HWID to the corresponding key file 82 duringupdating), throughput in producing such bb.dll's 80 by the black boxserver 36 is significantly increased, with little if any real reductionin overall security.

Further Concepts—Backup and Restore

As was just discussed, the black box 30 of the DRM system 32 includesthe (n)th key file 82 and the (n)th bb.dll 80 and is tightly tied to orassociated with the user's computing device 14 by including the HWIDfrom such computing device 14. Thus, each license 16 containing adecryption key (KD) encrypted according to a black box public key(PU-BB) stored in the (n)th key file 82 is also tightly tied to thecomputing device 14, as is the DRM system 32 itself. If the DRM system32 senses that the HWID of the computing device 14 is not the same HWIDspecified in the black box 30, such DRM system 32 concludes that it isnot for the computing device 14 and prohibits some if not all renderingof digital content 12 by such DRM system 12. Accordingly, a license 16issued to one DRM system 32 on a first user machine 14 is bound by a‘chain’ to the HWID of the first user machine 14 by way of the key file82 and cannot be employed in connection with a copied DRM client 32 on asecond machine 14.

However, on occasion, the HWID of the computing device 14 changesthrough no fault of the user and without any deceptive or nefariousintent on the part of the user. As but one example, the user may haveacquired a different computing device 14 with a different DRM system 32thereon. As other examples, the HWID may have become corrupted, may havebeen re-assigned, or otherwise may have changed due to a change in thecomputing device 14 such as a new operating system or a new piece ofhardware or software. In such a situation, then, it is preferable that amechanism be available to re-establish the chain between each license 16and the changed HWID.

Generally, in the present invention, any such mechanism essentiallycontacts a backup/restore server and sends one or more files or the liketo such backup/restore server, where such files existed in connectionwith the prior HWID and were previously saved and include importanttying information. Such backup/restore server then alters each file orcreates new corresponding files and then returns such files to the DRMsystem 32, where such altered/new files appropriately re-establish thechain between each license 16 and the changed HWID of the computingdevice 14 upon which the DRM system 32 resides.

Remember now that a piece of digital content 12 is encrypted accordingto a decryption key (KD). Remember also that a corresponding license 16issued for a DRM system 32 contains the decryption key (KD) encryptedaccording to a black box public key (PU-BB), Remember in addition thatPU-BB (if old) is expected to be in the key file 82 of the black box 30of such DRM system 32. Remember further that the key file 82 includesthe HWID of the computing system 14 upon which the DRM system 32resides. Now, if the HWID were to change, either because the computingdevice 14 has legitimately changed, or for some other legitimate reason,two scenarios can occur: the same DRM system 32 with the same black box30 and the same key file 82 exists in connection with the new HWID, or anew DRM system 32 with a new black box 30 and a ‘pristine’ key file 82exists is installed in connection with the new HWID.

In the former case, the new key file 82 has the wrong HWID, but has theold key sets having the old keys for the older licenses 16. Thus, thelink in the chain between each license 16 and the computing device 14that is missing is the correct HWID. In the latter case, the new keyfile 82 has the right HWID, but does not have the old key sets havingthe old keys for the older licenses 16. Thus, the link in the chainbetween each license 16 and the computing device 14 that is missing isthe necessary old key sets in the old key file 82. It is necessary,then, at least in the latter case, to maintain a saved copy of the oldkey file 82. However, to adequately address either case with a singleprotocol, it is necessary to maintain a saved copy of the old key file82, as will be explained in detail below. Any particular mechanism maybe employed to save such copy of the old key file 82 without departingfrom the spirit and scope of the present invention.

In particular, in one embodiment of the present invention, each license16 is re-tied to the computing device 14 by employing the aforementionedbackup/restore server to appropriately alter the HWID in such old keyfile 82 to correspond to the current HWID of the computing device 14upon which the DRM system 32 resides, and then by appropriatelyinstalling such old key file 82 in such DRM system 32. As should beappreciated, such protocol adequately addresses each of theaforementioned cases. Here, the black box server 26 may act as theaforementioned backup/restore server, although another server such as adedicated server may be employed without departing from the spirit andscope of the present invention.

Referring now to FIG. 21, in such embodiment, when a backup/restorefunction is necessary due to a changed HWID on a computing system 14 ordue to a new HWID on a new computing system 14, the DRM system 32 sendsa backup/restore request to the black box server 26 acting as thebackup/restore server (step 2101). Such request may be sentautomatically or upon approval by the user of the computing device 14.The user may also actively initiate the request without departing fromthe spirit and scope of the present invention. As was discussed above,the request includes the old key file 82 (i.e., the saved copy havingthe necessary old key sets) and the new/changed HWID (i.e., ‘the newHWID’). Of course, the request may also include other informationwithout departing from the spirit and scope of the present invention.

In response to the request, the backup/restore server (black box server26) locates the HWID already present in the old key file 82 (i.e., ‘theold HWID’)and appropriately replaces such old HWID with the new HWID(steps 2103, 2105), and then sends the changed old key file 82 back tothe DRM system 32 (step 2107). Preferably, the old key sets stored insuch changed old key file 82 are not altered in the course of changingthe HWID therein. Accordingly, such old key sets will be available tolicenses 16 stored on the DRM system 32 when the changed old key file 82is appropriately installed in the DRM system 32 residing on thecomputing device 14 at issue.

In one particular form of the present embodiment, the location andreplacement of the old HWID (steps 2103, 2105) is performed essentiallyas a stand-alone operation so that the old key file 82 is not otherwisemodified. Of course, even if only the old HWID in such old key file 82is replaced with the new HWID, any items in the old key file 82 thatrely on such old HWID must also be altered. For example, digitalcertificates and/or digital signatures in the old key file 82 that arebased at least in part on the old HWID must be altered or re-writtenbased on the new HWID. Moreover, the bb.dll 80 corresponding to the oldkey file 82 must also be altered if it relies on such old HWID. Forexample, and as was discussed above, the old HWID may have been injectedinto the corresponding bb.dll 80, and may be employed as anothermechanism to tie the black box 30 containing such bb.dll 80 to thecomputing device 14 upon which the DRM system resides.

As should be appreciated, then, it may be exceedingly difficult toperform each and every necessary alteration with respect to the old HWIDin both the old key file 82 and the corresponding bb.dll 80. Further,such alterations quickly become cumbersome if the bb.dll 80 must bedelivered to the backup/restore server as part of the request (step2101). In addition, it may very well be the case that such alterationsare all but impossible to perform, such as for example if the old HWIDwas injected into the corresponding bb.dll 80 and now must be locatedwithout the assistance of any help file, or if the corresponding bb.dll80 is not available.

Accordingly, in a preferred embodiment of the present embodiment, there-tying is performed as part of a black box upgrade by the structure ofFIG. 19 and in the manner shown in FIGS. 20A-20C. As should beappreciated, though, such a ‘re-tie upgrade’ differs from a ‘regularupgrade’ in that the (n−1)th key file 82 is not forwarded to the keymanager 84, as in a regular upgrade (step 2005, FIG. 20A). Instead, andas seen in FIG. 20D, the aforementioned saved copy of the old key file82 is forwarded (step 2005′ of FIG. 20D). Also, such a ‘re-tie upgrade’differs from a ‘regular upgrade’ in that the HWID obtained is not theold HWID from the (n−1)th key file 92, as in a regular upgrade (step2021, FIG. 20B). Instead, and as seen in FIG. 20D, such HWID obtainedduring a re-tie upgrade is the new HWID, and such new HWID is obtainedfrom information received as part of the request (step 2021′ of FIG.20D). Otherwise, the re-tie upgrade in such embodiment is substantiallythe same as the regular upgrade. As should now be apparent, such re-tieupgrade is a relatively simple way to alter the HWID in the key file 82since the structure of FIG. 19 and the steps of FIGS. 20A-20C (includingof course the substitutions in FIG. 20D) generally take care of alldetails regarding the placement of the new HWID in the normal course ofperforming the upgrade. Moreover, a re-tie upgrade has the added benefitof providing the requesting DRM system 32 with an upgraded black box 30.

The changed key file 82 (or upgraded black box 30 with re-tied key file82) is received by the DRM system 32 from the backup/restore server andappropriately installed in such DRM system 32 as part of the black box30 (step 2109 of FIG. 21, steps 2045′, 2047′ of FIG. 20D). The chainbetween each license 16 and the new HWID of the computing device 14 uponwhich the DRM system 32 resides is now complete. In particular, eachlicense 16 contains a decryption key (KD) encrypted according to a blackbox public key (PU-BB) stored in the changed key file 82 (or upgradedblack box 30 with re-tied key file 82), and therefore is tied thereto.Correspondingly, the black box 30 of the DRM system 32 includes thechanged key file 82 (or upgraded black box 30 with re-tied key file 82)which now includes the new HWID of the computing device 14, andtherefore is tied to such computing device 14.

In one embodiment of the present invention, rather than altering orupgrading the key file 82/black box 30 to complete the chain betweeneach license 16 and the new HWID of the computing device 14, eachexisting digital license 16 associated with the DRM system 32 isre-written to be tied to the black box 30. This of course assumes thatsuch black box 30 of such DRM system 32 is tied to the proper HWID. Inparticular, the decryption key encrypted by an old PU-BB (PU-BB[old](KD)) in the license is replaced by such decryption key encrypted by thePU-BB of the properly tied black box 30 of the DRM system 32 (PU-BB[new](KD)). Here, again, the aforementioned copy of the old key file 82 mustbe saved, for reasons will be explained below.

To re-write a license 16 in the present embodiment, then, and referringto FIG. 22, the DRM system 32 at issue sends the license 16 to abackup/restore server, along with the copy of the old key file 82, and acopy of (PU-BB[new]), perhaps in the form of an appropriate certificate(step 2201) (i.e., the same information that is normally sent to thelicense server 24 during a request for a license 16). Of course,multiple licenses 16 may be sent to the backup/restore server forre-writing without departing from the spirit and scope of the presentinvention. Here, the backup/restore server may be the license server 24,the black box server 26, or another server, such as for example adedicated server, without departing from the spirit and scope of thepresent invention.

The backup/restore server here extracts (PU-BB[old] (KD)) from thelicense 16 (step 2203), extracts the old key sets from the old key file82 in a manner akin to that discussed above in connection with step 2011of FIG. 20B (step 2205), locates the (PR-BB[old]) corresponding to the(PU-BB[old]) of (PU-BB[old] (KD)) from the license 16 (step 2207),applies (PR-BB[old]) to (PU-BB[old] (KD)) to obtain (KD) (step 2209),encrypts (KD) based on (PU-BB[new]) to produce (PU-BB[new] (KD)) (step2211), and then inserts such (PU-BB[new] (KD)) back into the license 16(step 2213). Such re-written license 16 with (PU-BB[new] (KD)) may thenbe signed and returned to the DRM system 32 at issue (step 2215) andstored in the license store 38 (FIG. 4) (step 2217).

The chain between the re-written license 16 as received from thebackup/restore server and the new HWID of the computing device 14 uponwhich the DRM system 32 resides is now complete. In particular, thelicense 16 contains a decryption key (KD) encrypted according to theblack box public key (PU-BB[new]) of the black box 30 of the new DRMsystem 32, and therefore is tied thereto. Correspondingly, the black box30 of the new DRM system 32 includes a key file 82 which includes thenew HWID of the computing device 14, and therefore is tied to suchcomputing device 14.

It is to be noted that the present embodiment requires that each license16 be individually re-written. This of course can be quite cumbersomeand time-consuming. However, the present embodiment does have asignificant advantage in that each existing license 16 may include anoption to prevent such re-writing. Of course, such option would bespecified by the issuer of the license 16.

In another embodiment of the present invention, rather than re-writingeach license 16, such license 16 is re-issued by the issuing licenseserver 24 in the manner set forth above. As before, each existinglicense 16 may include an option to prevent such re-issuance. Of course,re-issuance cannot take place if the license server 24 no longer is ableto re-issue the license 16 for any of a variety of reasons.

In a further embodiment of the present invention, rather than having abackup/restore server re-write each license 16, each license 16 isre-written by the DRM system 32 itself. As should be appreciated, suchre-writing by the DRM system 32 is possible if a backup/restore serveris employed to extract the old key sets from the old key file 82 in amanner akin to that discussed above in connection with step 2011 of FIG.20B. Otherwise, the DRM system 32 and the black box 30 thereof hasaccess to all keys necessary to perform such re-writing. Of course,providing the DRM system 32 with the functionality to re-write a license16 in the manner disclosed herein must be done guardedly. Specifically anefarious entity must not be allowed to employ such functionality to ineffect issue new licenses 16.

As may be appreciated, a backup/restore server may be employed in any ofthe manners discussed above to legitimately copy a black box 30 of a DRMsystem 32 to other computing devices 14, or to legitimately re-writelicenses 16 to work on other DRM systems 32. In the former instance, forexample, a key file 82 from a first computing device 14 may be employedas the old key file 82 in connection with a backup/restore of a seconddevice 14, thereby in effect allowing the second device 14 to employlicenses 16 written for the first device to render digital content 12 onsuch second device 14. Accordingly, a user can render digital content 12on multiple machines 14 under his/her control.

Of course, a nefarious entity may use the backup/restore server and thesame techniques to illegitimately copy a black box 30 of a DRM system 32to other computing devices 14, or to illegitimately re-write licenses 16to work on other DRM systems 32. Preferably, then, the backup/restoreserver includes an appropriate fraud detection mechanism to prevent orat least curtail such illegitimate activities. For example, thebackup/restore server may access a fraud detection database in which itnotes the key sets in each backup/restore request, and may be programmedto refuse a backup/restore request if the key sets in the request showup too often, such as for example more than three times in a six monthperiod. Of course, other frequencies and periods may be employed withoutdeparting from the spirit and scope of the present invention.

CONCLUSION

The programming necessary to effectuate the processes performed inconnection with the present invention is relatively straight-forward andshould be apparent to the relevant programming public. Accordingly, suchprogramming is not attached hereto. Any particular programming, then,may be employed to effectuate the present invention without departingfrom the spirit and scope thereof.

In the foregoing description, it can be seen that the present inventioncomprises a new and useful enforcement architecture 10 that allows thecontrolled rendering or playing of arbitrary forms of digital content12, where such control is flexible and definable by the content owner ofsuch digital content 12. Also, the present invention comprises a newuseful controlled rendering environment that renders digital content 12only as specified by the content owner, even though the digital content12 is to be rendered on a computing device 14 which is not under thecontrol of the content owner. Further, the present invention comprises atrusted component that enforces the rights of the content owner on suchcomputing device 14 in connection with a piece of digital content 12,even against attempts by the user of such computing device 14 to accesssuch digital content 12 in ways not permitted by the content owner.

It should be appreciated that changes could be made to the embodimentsdescribed above without departing from the inventive concepts thereof.It should be understood, therefore, that this invention is not limitedto the particular embodiments disclosed, but it is intended to covermodifications within the spirit and scope of the present invention asdefined by the appended claims.

1-46. (Cancelled)
 47. A computer-readable medium havingcomputer-executable instructions for producing a key (KD) for decryptinga digital object, the digital object having been encrypted by: selectinga key ID for the digital object; selecting a function f( ) having aninput and an output; employing the selected key ID as the input to thefunction f( ); employing the output of such function f( ) as the key(KD) for the digital object: f(key ID)

key (KD), encrypting such digital object according to such key (KD); anddistributing such encrypted digital object, along with the key ID, themethod comprising: receiving a request for the key (KD) from arequester, the request including the key ID; approving the request;employing the included key ID as the input to the function f( );employing the output of such function f( ) as the requested key (KD):f(key ID)

key (KD); and distributing such key (KD) to the requestor.
 48. Thecomputer-readable medium of claim 47 wherein the computer-executableinstructions further perform employing the selected key ID along with asecret seed as the input to the function f( ): f(key ID, seed)

key (KD), both when producing the key (KD) to encrypt the digital objectand when producing the key (KD) to distribute to the requestor.
 49. Thecomputer-readable medium of claim 48 wherein the seed has a seed ID, andwherein the method comprises employing the selected key ID and thesecret seed along with the seed ID as the input to the function f( ):f(key ID, seed, seed ID

key (KD), both when producing the key (KD) to encrypt the digital objectand when producing the key (KD) to distribute to the requestor.
 50. Thecomputer-readable medium of claim 47 wherein the computer-executableinstructions further perform selecting a one-way function f( ).
 51. Thecomputer-readable medium of claim 50 wherein the computer-executableinstructions further perform selecting a one-way functions) from a groupconsisting of a secure hashing algorithm (SHA) or an MD5 algorithm. 52.The computer-readable medium of claim 47 wherein the computer-executableinstructions further perform: receiving a license request for a digitallicense including the key (KD) from a license requestor, the licenserequest including the key ID; approving the license request; employingthe included key ID as the input to the function f( ); employing theoutput of such function f( ) as the requested key (KD): f(key ID)

key (KD); and distributing such key (KD) to the license requestor aspart of a digital license.
 53. The computer-readable medium of claim 47wherein the computer-executable instructions further perform receivingthe selected function f( ).
 54. The computer-readable medium of claim 53wherein the key ID is employed along with a secret seed as the input tothe function f( ): f(key ID, seed)

key (KD), when producing the key (KD) to encrypt the digital object, themethod comprising: receiving the selected function f( ) and the secretseed; and employing the included key ID along with the received secretseed as the input to the received function f( ): f(key ID, seed)

key (KD), when producing the key (KD) to distribute to the requestor.55. The computer-readable medium of claim 54 wherein the secret seed hasa seed ID, and wherein the key ID, the secret seed, and the seed ID areemployed as the input to the function f( ): f(key ID, seed, seed ID)

key (KD), when producing the key (KD) to encrypt the digital object, themethod comprising: receiving the selected function f( ), the secretseed, and the seed ID thereof; receiving the request for the key (KD)including the key ID and the seed ID as distributed along with theencrypted digital object; selecting the secret seed based on thereceived seed ID; and employing the included key ID, the included seedID, and the selected seed as the input to the received function f( ):f(key ID, seed, seed ID)

key (KD), when producing the key (KD) to distribute to the requestor.56. A method of requesting a key (KD) for decrypting a digital object,the digital object having been encrypted by: means for selecting a keyID for the digital object; means for selecting a function f( ) having aninput and an output; means for employing the selected key ID as theinput to the function f( ); means for employing the output of suchfunction f( ) as the key (KD) for the digital object: f(key ID)

key (KD), means for encrypting such digital object according to such key(KD); and means for distributing such encrypted digital object, alongwith the key ID, the method comprising: receiving the distributedencrypted digital object, along with the key ID; obtaining the key IDfrom same; and sending a request for the key (KD), the request includingthe key ID, wherein upon approval of the request, the included key ID isemployed as the input to the function f( ); and the output of suchfunction f( ) is employed as the requested key (KD): f(key ID)

key (KD); and such key (KD) being distributed, the method furthercomprising receiving the distributed key (KD).
 57. The method of claim56 for requesting a digital license including the key (KD) fordecrypting the digital object, the method comprising: means for sendinga request for the digital license including the key (KD), the requestincluding the key ID, wherein upon approval of the request, the includedkey ID is employed as the input to the function f( ); and the output ofsuch function f( ) is employed as the requested key (KD): f(key ID)

key (KD); and such key (KD) being distributed as part of the requesteddigital license, the method further comprising receiving the digitallicense including the distributed key (KD).
 58. The method of claim 56wherein the digital object has been encrypted by: selecting a key ID forthe digital object; selecting a secret seed having a seed ID selecting afunction f( ) having an input and an output; employing the selected keyID and the selected seed as the input to the function f( ); employingthe output of such function f( ) as the key (KD) for the digital object:f(key ID, seed)

key (KD), encrypting such digital object according to such key (KD); anddistributing such encrypted digital object, along with the key ID andthe seed ID, the method comprising: receiving the distributed encrypteddigital object, along with the key ID and the seed ID; obtaining the keyID and seed ID from same; and sending a request for the key (KD), therequest including the key ID and seed ID, wherein upon approval of therequest, the secret seed is selected based on the received seed ID; theincluded key ID and the selected secret seed are employed as the inputto the function f( ); and the output of such function f( ) is employedas the requested key (KD): f(key ID, seed)

key (KD), such key (KD) being distributed, the method further comprisingreceiving the distributed key (KD).
 59. The method of claim 58 whereinthe digital object has been encrypted by: selecting a key ID for thedigital object; selecting a secret seed having a seed ID selecting afunction f( ) having an input and an output; employing the selected keyID, the selected seed, and the seed ID thereof as the input to thefunction f( ); employing the output of such function f( ) as the key(KD) for the digital object: f(key ID, seed, seed ID)

key (KD), encrypting such digital object according to such key (KD); anddistributing such encrypted digital object, along with the key ID andthe seed ID, the method comprising: receiving the distributed encrypteddigital object, along with the key ID and the seed ID; obtaining the keyID and seed ID from same; and sending a request for the key (KD), therequest including the key ID and seed ID, wherein upon approval of therequest, the secret seed is selected based on the received seed ID; theincluded key ID, the included seed ID, and the selected secret seed areemployed as the input to the function f( ); and the output of suchfunction f( ) is employed as the requested key (KD): f(key ID, seed,seed ID)

key (KD), such key (KD) being distributed, the method further comprisingreceiving the distributed key (KD).